大道至简，上善若水
how to use coffee-script
CoffeeScript is a little language that compiles into JavaScript.&Underneath all those awkward braces and semicolons, JavaScript has always had a gorgeous object model at its heart. CoffeeScript is an attempt to expose
the good parts of JavaScript in a simple way.
The golden rule of CoffeeScript is:&&It's just JavaScript&. The code compiles one-to-one into the equivalent JS, and there is no interpretation at runtime. You can use any existing JavaScript library seamlessly from CoffeeScript
(and vice-versa). The compiled output is readable and pretty-printed, passes through&&without warnings, will work in every JavaScript runtime, and tends to run as fast
or faster than the equivalent handwritten JavaScript.
Latest Version:&
CoffeeScript on the left, compiled JavaScript output on the right.
Assignment:
opposite = true
Conditions:
number = -42 if opposite
Functions:
square = (x) -& x * x
list = [1, 2, 3, 4, 5]
square: square
(x) -& x * square x
race = (winner, runners...) -&
print winner, runners
Existence:
alert &I knew it!& if elvis?
Array comprehensions:
cubes = (math.cube num for num in list)
var cubes, list, math, num, number, opposite, race, square,
__slice = [].
number = 42;
opposite = true;
if (opposite) {
number = -42;
square = function(x) {
return x *
list = [1, 2, 3, 4, 5];
root: Math.sqrt,
square: square,
cube: function(x) {
return x * square(x);
race = function() {
var runners,
winner = arguments[0], runners = 2 &= arguments.length ? __slice.call(arguments, 1) : [];
return print(winner, runners);
if (typeof elvis !== &undefined& && elvis !== null) {
alert(&I knew it!&);
cubes = (function() {
var _i, _len, _
_results = [];
for (_i = 0, _len = list.length; _i & _ _i++) {
num = list[_i];
_results.push(math.cube(num));
run: cubes
Installation
The CoffeeScript compiler is itself&, using the&. The command-line version of&coffee&is
available as a&&utility. The&however, does not depend on Node, and
can be run in any JavaScript environment, or in the browser (see &Try CoffeeScript&, above).
To install, first make sure you have a working copy of the latest stable version of&, and&&(the Node Package
Manager). You can then install CoffeeScript with npm:
npm install -g coffee-script
(Leave off the&-g&if
you don't wish to install globally.)
If you'd prefer to install the latest&master&version of CoffeeScript, you can clone the CoffeeScript&&from GitHub, or
download&&directly. To install the lastest master CoffeeScript compiler with npm:
npm install -g http://github.com/jashkenas/coffee-script/tarball/master
Or, if you want to install to&/usr/local,
and don't want to use npm to manage it, open the&coffee-script&directory
sudo bin/cake install
Once installed, you should have access to the&coffee&command,
which can execute scripts, compile&.coffee&files
and provide an interactive REPL. The&coffee&command
takes the following options:
-c, --compile
Compile a&.coffee&script
into a&.js&JavaScript file
of the same name.
-i, --interactive
Launch an interactive CoffeeScript session to try short snippets. Identical to calling&coffee&with
no arguments.
-o, --output [DIR]
Write out all compiled JavaScript files into the specified directory. Use in conjunction with&--compile&or&--watch.
-j, --join [FILE]
Before compiling, concatenate all scripts together in the order they were passed, and write them into the specified file. Useful for building large projects.
-w, --watch
Watch files for changes, rerunning the specified command when any file is updated.
-p, --print
Instead of writing out the JavaScript as a file, print it directly tostdout.
-l, --lint
If the&jsl&() command is installed, use it to check the compilation of a CoffeeScript file. (Handy in conjunction with&
-s, --stdio
Pipe in CoffeeScript to STDIN and get back JavaScript over STDOUT. Good for use with processes written in other languages. An example:
cat src/cake.coffee | coffee -sc
-e, --eval
Compile and print a little snippet of CoffeeScript directly from the command line. For example:
coffee -e &console.log num for
num in [10..1]&
-r, --require
Load a library before compiling or executing your script. Can be used to hook in to the compiler (to add Growl notifications, for example).
-b, --bare
Compile the JavaScript without the&.
-t, --tokens
Instead of parsing the CoffeeScript, just lex it, and print out the token stream:&[IDENTIFIER
square] [ASSIGN =] [PARAM_START (]&...
-n, --nodes
Instead of compiling the CoffeeScript, just lex and parse it, and print out the parse tree:
Expressions
Value &square&
The&node&executable
has some useful options you can set, such as
--debug,&--debug-brk&and&--max-stack-size.
Use this flag to forward options directly to Node.js.
Compile a directory tree of&.coffee&files
in&src&into
a parallel tree of&.js&files
coffee --compile
--output lib/ src/Watch a file for changes, and recompile it every time the file is saved:
coffee --watch
--compile experimental.coffeeConcatenate a list of files into a single script:
coffee --join project.js
--compile src/*.coffeePrint out the compiled JS from a one-liner:
coffee -bpe &alert
i for i in [0..10]&All together now, watch and recompile an entire project as you work on it:
coffee -o lib/
-cw src/Start the CoffeeScript REPL (Ctrl-D&to
exit,&Ctrl-Vfor
multi-line):
Language Reference
This reference is structured so that it can be read from top to bottom, if you like. Later sections use ideas and syntax previously introduced. Familiarity with JavaScript is assumed. In all of the following examples, the source CoffeeScript
is provided on the left, and the direct compilation into JavaScript is on the right.
Many of the examples can be run (where it makes sense) by pressing the&run&button on the right, and can be loaded into the &Try CoffeeScript& console by pressing the&load&button on the left.
First, the basics: CoffeeScript uses significant whitespace to delimit blocks of code. You don't need to use semicolons&;&to
terminate expressions, ending the line will do just as well (although semicolons can still be used to fit multiple expressions onto a single line). Instead of using curly braces&{
}&to surround blocks of code in&,&,,
and&, use indentation.
You don't need to use parentheses to invoke a function if you're passing arguments. The implicit call wraps forward to the end of the line or block expression.
console.log sys.inspect
object&→&console.log(sys.inspect(object));
are defined by an optional list of parameters in parentheses, an arrow, and the function body. The empty function looks like this:&-&
square = (x) -& x * x
= (x) -& square(x) * x
square = function(x) {
return x *
cube = function(x) {
return square(x) *
run: cube(5)
Functions may also have default values for arguments. Override the default value by passing a non-null argument.
fill = (container, liquid = &coffee&) -&
&Filling the #{container} with #{liquid}...&
fill = function(container, liquid) {
if (liquid == null) {
liquid = &coffee&;
return &Filling the & + container + & with & + liquid + &...&;
run: fill(&cup&)
The CoffeeScript literals for objects and arrays look very similar to their JavaScript cousins. When each property is listed on its own line, the commas are optional. Objects may be created using indentation instead of explicit braces, similar
song = [&do&, &re&, &mi&, &fa&, &so&]
singers = {Jagger: &Rock&, Elvis: &Roll&}
bitlist = [
name: &Max&
name: &Ida&
var bitlist, kids, singers,
song = [&do&, &re&, &mi&, &fa&, &so&];
singers = {
Jagger: &Rock&,
Elvis: &Roll&
bitlist = [1, 0, 1, 0, 0, 1, 1, 1, 0];
brother: {
name: &Max&,
name: &Ida&,
run: song.join(& ... &)
In JavaScript, you can't use reserved words, like&class,
as properties of an object, without quoting them as strings. CoffeeScript notices reserved words used as keys in objects and quotes them for you, so you don't have to worry about it (say, when using jQuery).
$('.account').attr class: 'active'
log object.class
$('.account').attr({
&class&: 'active'
log(object[&class&]);
The CoffeeScript compiler takes care to make sure that all of your variables are properly declared within lexical scope — you never need to write&var&yourself.
changeNumbers = -&
inner = -1
outer = 10
inner = changeNumbers()
var changeNumbers, inner,
outer = 1;
changeNumbers = function() {
inner = -1;
return outer = 10;
inner = changeNumbers();
run: inner
Notice how all of the variable declarations have been pushed up to the top of the closest scope, the first time they appear.&outer&is not redeclared within the inner function, because it'&inner&within
the function, on the other hand, should not be able to change the value of the external variable of the same name, and therefore has a declaration of its own.
This behavior is effectively identical to Ruby's scope for local variables. Because you don't have direct access to the&var&keyword,
it's impossible to shadow an outer variable on purpose, you may only refer to it. So be careful that you're not reusing the name of an external variable accidentally, if you're writing a deeply nested function.
Although suppressed within this documentation for clarity, all CoffeeScript output is wrapped in an anonymous function:&(function(){
... })();&This safety wrapper, combined with the automatic generation of the&var&keyword,
make it exceedingly difficult to pollute the global namespace by accident.
If you'd like to create top-level variables for other scripts to use, attach them as properties on&window, or on the&exports&object in CommonJS. The&existential operator&(covered below),
gives you a reliable way to figure o if you're targeting both CommonJS and the browser:&exports
&statements can be written without the use of parentheses and curly brackets. As with functions and other block expressions, multi-line conditionals are delimited by indentation. There's also a handy postfix
form, with the&if&or&unless&at
CoffeeScript can compile&if&statements into JavaScript expressions, using the ternary operator when possible, and closure wrapping otherwise. There is no explicit ternary statement in CoffeeScript — you simply use a regular&if&statement
on a single line.
mood = greatlyImproved if singing
if happy and knowsIt
clapsHands()
chaChaCha()
date = if friday then sue else jill
if (singing) {
mood = greatlyI
if (happy && knowsIt) {
clapsHands();
chaChaCha();
date = friday ? sue :
JavaScript&arguments object&is a useful way to work with functions that accept variable numbers of arguments. CoffeeScript provides splats&...,
both for function definition as well as invocation, making variable numbers of arguments a little bit more palatable.
gold = silver = rest = &unknown&
awardMedals = (first, second, others...) -&
silver = second
contenders = [
&Michael Phelps&
&Liu Xiang&
&Yao Ming&
&Allyson Felix&
&Shawn Johnson&
&Roman Sebrle&
&Guo Jingjing&
&Tyson Gay&
&Asafa Powell&
&Usain Bolt&
awardMedals contenders...
alert &Gold: & + gold
alert &Silver: & + silver
alert &The Field: & + rest
var awardMedals, contenders, gold, rest, silver,
__slice = [].
gold = silver = rest = &unknown&;
awardMedals = function() {
var first, others,
first = arguments[0], second = arguments[1], others = 3 &= arguments.length ? __slice.call(arguments, 2) : [];
return rest =
contenders = [&Michael Phelps&, &Liu Xiang&, &Yao Ming&, &Allyson Felix&, &Shawn Johnson&, &Roman Sebrle&, &Guo Jingjing&, &Tyson Gay&, &Asafa Powell&, &Usain Bolt&];
awardMedals.apply(null, contenders);
alert(&Gold: & + gold);
alert(&Silver: & + silver);
alert(&The Field: & + rest);
Most of the loops you'll write in CoffeeScript will be&comprehensions&over arrays, objects, and ranges. Comprehensions replace (and compile into)&for&loops, with optional guard clauses and the value
of the current array index. Unlike for loops, array comprehensions are expressions, and can be returned and assigned.
Eat lunch.
eat food for food in ['toast', 'cheese', 'wine']
Fine five course dining.
courses = ['greens', 'caviar', 'truffles', 'roast', 'cake']
menu i + 1, dish for dish, i in courses
Health conscious meal.
foods = ['broccoli', 'spinach', 'chocolate']
eat food for food in foods when food isnt 'chocolate'
var courses, dish, food, foods, i, _i, _j, _k, _len, _len1, _len2, _
_ref = ['toast', 'cheese', 'wine'];
for (_i = 0, _len = _ref.length; _i & _ _i++) {
food = _ref[_i];
eat(food);
courses = ['greens', 'caviar', 'truffles', 'roast', 'cake'];
for (i = _j = 0, _len1 = courses.length; _j & _len1; i = ++_j) {
dish = courses[i];
menu(i + 1, dish);
foods = ['broccoli', 'spinach', 'chocolate'];
for (_k = 0, _len2 = foods.length; _k & _len2; _k++) {
food = foods[_k];
if (food !== 'chocolate') {
eat(food);
Comprehensions should be able to handle most places where you otherwise would use a loop,&each/forEach,&map, or&select/filter, for example:shortNames
= (name for name in list when name.length & 5)
If you know the start and end of your loop, or would like to step through in fixed-size increments, you can use a range to specify the start and end of your comprehension.
countdown = (num for num in [10..1])
var countdown,
countdown = (function() {
_results = [];
for (num = _i = 10; _i &= 1; num = --_i) {
_results.push(num);
run: countdown
Note how because we are assigning the value of the comprehensions to a variable in the example above, CoffeeScript is collecting the result of each iteration into an array. Sometimes functions end with loops that are intended to run only
for their side-effects. Be careful that you're not accidentally returning the results of the comprehension in these cases, by adding a meaningful return value — like&true&—
to the bottom of your function.
To step through a range comprehension in fixed-size chunks, use&by,
for example:
evens = (x for
x in [0..10] by 2)
Comprehensions can also be used to iterate over the keys and values in an object. Use&ofto
signal comprehension over the properties of an object instead of the values in an array.
yearsOld = max: 10, ida: 9, tim: 11
ages = for child, age of yearsOld
&#{child} is #{age}&
var age, ages, child, yearsO
yearsOld = {
ages = (function() {
_results = [];
for (child in yearsOld) {
age = yearsOld[child];
_results.push(&& + child + & is & + age);
run: ages.join(&, &)
If you would like to iterate over just the keys that are defined on the object itself, by adding a&hasOwnProperty&check
to avoid properties that may be inherited from the prototype, use
for own key, value
The only low-level loop that CoffeeScript provides is the&while&loop. The main difference from JavaScript is that the&while&loop can be used as an expression, returning an array containing the result
of each iteration through the loop.
if this.studyingEconomics
while supply & demand
sell() until supply & demand
Nursery Rhyme
lyrics = while num -= 1
&#{num} little monkeys, jumping on the bed.
One fell out and bumped his head.&
var lyrics,
if (this.studyingEconomics) {
while (supply & demand) {
while (!(supply & demand)) {
lyrics = (function() {
_results = [];
while (num -= 1) {
_results.push(&& + num + & little monkeys, jumping on the bed.
One fell out and bumped his head.&);
run: lyrics.join(&\n&)
For readability, the&until&keyword is equivalent to&while
not, and the&loop&keyword is equivalent to&while
When using a JavaScript loop to generate functions, it's common to insert a closure wrapper in order to ensure that loop variables are closed over, and all the generated functions don't just share the final values. CoffeeScript provides
the&do&keyword,
which immediately invokes a passed function, forwarding any arguments.
for filename in list
do (filename) -&
fs.readFile filename, (err, contents) -&
compile filename, contents.toString()
var filename, _fn, _i, _
_fn = function(filename) {
return fs.readFile(filename, function(err, contents) {
return compile(filename, contents.toString());
for (_i = 0, _len = list.length; _i & _ _i++) {
filename = list[_i];
_fn(filename);
Ranges can also be used to extract slices of arrays. With two dots (3..6),
the range is inclusive (3,
4, 5, 6); with three dots (3...6),
the range excludes the end (3,
4, 5). Slices indices have useful defaults. An omitted first index defaults to zero and an omitted second index defaults to the size of the array.
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9]
= numbers[0..2]
= numbers[3...6]
= numbers[6..]
= numbers[..]
var copy, end, middle, numbers,
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9];
start = numbers.slice(0, 3);
middle = numbers.slice(3, 6);
end = numbers.slice(6);
copy = numbers.slice(0);
run: middle
The same syntax can be used with assignment to replace a segment of an array with new values, splicing it.
numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
numbers[3..6] = [-3, -4, -5, -6]
var numbers, _
numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
[].splice.apply(numbers, [3, 4].concat(_ref = [-3, -4, -5, -6])), _
run: numbers
Note that JavaScript strings are immutable, and can't be spliced.
You might have noticed how even though we don't add return statements to CoffeeScript functions, they nonetheless return their final value. The CoffeeScript compiler tries to make sure that all statements
in the language can be used as expressions. Watch how the&returngets
pushed down into each possible branch of execution in the function below.
grade = (student) -&
if student.excellentWork
else if student.okayStuff
if student.triedHard then &B& else &B-&
eldest = if 24 & 21 then &Liz& else &Ike&
var eldest,
grade = function(student) {
if (student.excellentWork) {
return &A+&;
} else if (student.okayStuff) {
if (student.triedHard) {
return &B&;
return &B-&;
return &C&;
eldest = 24 & 21 ? &Liz& : &Ike&;
run: eldest
Even though functions will always return their final value, it's both possible and encouraged to return early from a function body writing out the explicit return (return
value), when you know that you're done.
Because variable declarations occur at the top of scope, assignment can be used within expressions, even for variables that haven't been seen before:
six = (one = 1) + (two = 2) + (three = 3)
var one, six, three,
six = (one = 1) + (two = 2) + (three = 3);
Things that would otherwise be statements in JavaScript, when used as part of an expression in CoffeeScript, are converted into expressions by wrapping them in a closure. This lets you do useful things, like assign the result of a comprehension
to a variable:
The first ten global properties.
globals = (name for name of window)[0...10]
var globals,
globals = ((function() {
_results = [];
for (name in window) {
_results.push(name);
})()).slice(0, 10);
run: globals
As well as silly things, like passing a&try/catch&statement directly into a function call:
nonexistent / undefined
catch error
&And the error is ... #{error}&
alert((function() {
return nonexistent / void 0;
} catch (error) {
return &And the error is ... & +
There are a handful of statements in JavaScript that can't be meaningfully converted into expressions, namely&break,&continue,
and&return.
If you make use of them within a block of code, CoffeeScript won't try to perform the conversion.
Because the&==&operator
frequently causes undesirable coercion, is intransitive, and has a different meaning than in other languages, CoffeeScript compiles&==&into&===,
and&!=into&!==.
In addition,&is&compiles
and&isnt&into&!==.
You can use&not&as
an alias for&!.
For logic,&and&compiles
to&&&, and&or&into&||.
Instead of a newline or semicolon,&then&can
be used to separate conditions from expressions, in&while,&if/else, and&switch/when&statements.
As in&,&on&and&yes&are
the same as boolean&true,
while&off&and&no&are
boolean&false.
unless&can
be used as the inverse of&if.
As a shortcut for&this.property,
you can use&@property.
You can use&in&to
test for array presence, and&of&to
test for JavaScript object-key presence.
All together now:
CoffeeScript
JavaScript
no JS equivalent
launch() if ignition is on
volume = 10 if band isnt SpinalTap
letTheWildRumpusBegin() unless answer is no
if car.speed & limit then accelerate()
winner = yes if pick in [47, 92, 13]
print inspect &My name is #{@name}&
var volume,
if (ignition === true) {
if (band !== SpinalTap) {
volume = 10;
if (answer !== false) {
letTheWildRumpusBegin();
if (car.speed & limit) {
accelerate();
if (pick === 47 || pick === 92 || pick === 13) {
winner = true;
print(inspect(&My name is & + this.name));
It's a little difficult to check for the existence of a variable in JavaScript.&if
(variable) ...comes close, but fails for zero, the empty string, and false. CoffeeScript's existential operator&?&returns
true unless a variable is&null&or&undefined, which makes it analogous to Ruby's&nil?
It can also be used for safer conditional assignment than&||=&provides,
for cases where you may be handling numbers or strings.
solipsism = true if mind? and not world?
speed ?= 15
footprints = yeti ? &bear&
var footprints, solipsism,
if ((typeof mind !== &undefined& && mind !== null) && !(typeof world !== &undefined& && world !== null)) {
solipsism = true;
speed = 0;
if (speed == null) {
speed = 15;
footprints = typeof yeti !== &undefined& && yeti !== null ? yeti : &bear&;
run: footprints
The accessor variant of the existential operator&?.&can
be used to soak up null references in a chain of properties. Use it instead of the dot accessor&.&in
cases where the base value may be&null&or&undefined. If all of the properties exist then you'll get the expected result, if the chain is broken,&undefined&is returned instead of the&TypeError&that
would be raised otherwise.
zip = lottery.drawWinner?().address?.zipcode
var zip, _
zip = typeof lottery.drawWinner === &function& ? (_ref = lottery.drawWinner().address) != null ? _ref.zipcode : void 0 : void 0;
Soaking up nulls is similar to Ruby's&, and to the&&in Groovy.
JavaScript's prototypal inheritance has always been a bit of a brain-bender, with a whole family tree of libraries that provide a cleaner syntax for classical inheritance on top of JavaScript's prototypes:&,&,&,
etc. The libraries provide syntactic sugar, but the built-in inheritance would be completely usable if it weren't for a couple of small exceptions: it's awkward to call&super&(the prototype object's implementation of the current function),
and it's awkward to correctly set the prototype chain.
Instead of repetitively attaching functions to a prototype, CoffeeScript provides a basic&class&structure
that allows you to name your class, set the superclass, assign prototypal properties, and define the constructor, in a single assignable expression.
Constructor functions are named, to better support helpful stack traces. In the first class in the example below,&this.constructor.name
is &Animal&.
class Animal
constructor: (@name) -&
move: (meters) -&
alert @name + & moved #{meters}m.&
class Snake extends Animal
alert &Slithering...&
class Horse extends Animal
alert &Galloping...&
sam = new Snake &Sammy the Python&
tom = new Horse &Tommy the Palomino&
sam.move()
tom.move()
var Animal, Horse, Snake, sam, tom,
__hasProp = {}.hasOwnProperty,
__extends = function(child, parent) { for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return };
Animal = (function() {
function Animal(name) {
this.name =
Animal.prototype.move = function(meters) {
return alert(this.name + (& moved & + meters + &m.&));
Snake = (function(_super) {
__extends(Snake, _super);
function Snake() {
return Snake.__super__.constructor.apply(this, arguments);
Snake.prototype.move = function() {
alert(&Slithering...&);
return Snake.__super__.move.call(this, 5);
})(Animal);
Horse = (function(_super) {
__extends(Horse, _super);
function Horse() {
return Horse.__super__.constructor.apply(this, arguments);
Horse.prototype.move = function() {
alert(&Galloping...&);
return Horse.__super__.move.call(this, 45);
})(Animal);
sam = new Snake(&Sammy the Python&);
tom = new Horse(&Tommy the Palomino&);
sam.move();
tom.move();
If structuring your prototypes classically isn't your cup of tea, CoffeeScript provides a couple of lower-level conveniences. The&extends&operator
helps with proper prototype setup, and can be used to create an inheritance chain between any pair of c&::&gives
you quick access to an object' and&super()&is
converted into a call against the immediate ancestor's method of the same name.
String::dasherize = -&
this.replace /_/g, &-&
String.prototype.dasherize = function() {
return this.replace(/_/g, &-&);
run: &one_two&.dasherize()
Finally, class definitions are blocks of executable code, which make for interesting metaprogramming possibilities. Because in the context of a class definition,&this&is
the class object itself (the constructor function), you can assign static properties by using&
@property: value,
and call functions defined in parent classes:&@attr
'title', type: 'text'
To make extracting values from complex arrays and objects more convenient, CoffeeScript implements ECMAScript Harmony's proposed&&syntax. When you assign an array or object literal to a value, CoffeeScript breaks up and matches both sides against each other, assigning the values on the right to the variables on the left. In the simplest case, it can be used for parallel
assignment:
theSwitch = 0
[theBait, theSwitch] = [theSwitch, theBait]
var theBait, theSwitch, _
theBait = 1000;
theSwitch = 0;
_ref = [theSwitch, theBait], theBait = _ref[0], theSwitch = _ref[1];
run: theBait
But it's also helpful for dealing with functions that return multiple values.
weatherReport = (location) -&
Make an Ajax request to fetch the weather...
[location, 72, &Mostly Sunny&]
[city, temp, forecast] = weatherReport &Berkeley, CA&
var city, forecast, temp, weatherReport, _
weatherReport = function(location) {
return [location, 72, &Mostly Sunny&];
_ref = weatherReport(&Berkeley, CA&), city = _ref[0], temp = _ref[1], forecast = _ref[2];
run: forecast
Destructuring assignment can be used with any depth of array and object nesting, to help pull out deeply nested properties.
futurists =
sculptor: &Umberto Boccioni&
&Vladimir Burliuk&
&F.T. Marinetti&
address: [
&Via Roma 42R&
&Bellagio, Italy 22021&
{poet: {name, address: [street, city]}} = futurists
var city, futurists, name, street, _ref, _ref1;
futurists = {
sculptor: &Umberto Boccioni&,
painter: &Vladimir Burliuk&,
name: &F.T. Marinetti&,
address: [&Via Roma 42R&, &Bellagio, Italy 22021&]
_ref = futurists.poet, name = _ref.name, (_ref1 = _ref.address, street = _ref1[0], city = _ref1[1]);
run: name + & — & + street
Destructuring assignment can even be combined with splats.
tag = &&impossible&&
[open, contents..., close] = tag.split(&&)
var close, contents, open, tag, _i, _ref,
__slice = [].
tag = &&impossible&&;
_ref = tag.split(&&), open = _ref[0], contents = 3 &= _ref.length ? __slice.call(_ref, 1, _i = _ref.length - 1) : (_i = 1, []), close = _ref[_i++];
run: contents.join(&&)
In JavaScript, the&this&keyword
is dynamically scoped to mean the object that the current function is attached to. If you pass a function as a callback or attach it to a different object, the original value of&this&will
be lost. If you're not familiar with this behavior,&&gives a good overview of the quirks.
The fat arrow&=&&can
be used to both define a function, and to bind it to the current value of&this,
right on the spot. This is helpful when using callback-based libraries like Prototype or jQuery, for creating iterator functions to pass to&each,
or event-handler functions to use with&bind.
Functions created with the fat arrow are able to access properties of the&this&where
they're defined.
Account = (customer, cart) -&
@customer = customer
@cart = cart
$('.shopping_cart').bind 'click', (event) =&
@customer.purchase @cart
Account = function(customer, cart) {
var _this = this;
this.customer =
this.cart =
return $('.shopping_cart').bind('click', function(event) {
return _this.customer.purchase(_this.cart);
If we had used&-&&in
the callback above,&@customer&would
have referred to the undefined &customer& property of the DOM element, and trying to call&purchase()&on
it would have raised an exception.
When used in a class definition, methods declared with the fat arrow will be automatically bound to each instance of the class when the instance is constructed.
Hopefully, you'll never need to use it, but if you ever need to intersperse snippets of JavaScript within your CoffeeScript, you can use backticks to pass it straight through.
hi = `function() {
return [document.title, &Hello JavaScript&].join(&: &);
hi = function() {
return [document.title, &Hello JavaScript&].join(&: &);
&statements
in JavaScript are a bit awkward. You need to remember to&break&at the end of every&case&statement to avoid accidentally falling through to the default case. CoffeeScript prevents accidental fall-through, and can convert the&switch&into
a returnable, assignable expression. The format is:&switch&condition,&when&clauses,&else&the
default case.
As in Ruby,&switch&statements in CoffeeScript can take multiple values for each&whenclause. If any of the values match, the clause runs.
switch day
when &Mon& then go work
when &Tue& then go relax
when &Thu& then go iceFishing
when &Fri&, &Sat&
if day is bingoDay
go dancing
when &Sun& then go church
else go work
switch (day) {
case &Mon&:
case &Tue&:
go(relax);
case &Thu&:
go(iceFishing);
case &Fri&:
case &Sat&:
if (day === bingoDay) {
go(bingo);
go(dancing);
case &Sun&:
go(church);
statements are just about the same as JavaScript (although they work as expressions).
allHellBreaksLoose()
catsAndDogsLivingTogether()
catch error
print error
allHellBreaksLoose();
catsAndDogsLivingTogether();
} catch (error) {
print(error);
} finally {
cleanUp();
CoffeeScript borrows&&from Python — making it easy to test if a value falls within a certain range.
cholesterol = 127
healthy = 200 & cholesterol & 60
var cholesterol,
cholesterol = 127;
healthy = (200 & cholesterol && cholesterol & 60);
run: healthy
Ruby-style string interpolation is included in CoffeeScript. Double-quoted strings allow for interpolated values, using&#{
... }, and single-quoted strings are literal.
author = &Wittgenstein&
= &A picture is a fact. -- #{ author }&
sentence = &#{ 22 / 7 } is a decent approximation of π&
var author, quote,
author = &Wittgenstein&;
quote = &A picture is a fact. -- & +
sentence = && + (22 / 7) + & is a decent approximation of π&;
run: sentence
Multiline strings are allowed in CoffeeScript.
mobyDick = &Call me Ishmael. Some years ago --
never mind how long precisely -- having little
or no money in my purse, and nothing particular
to interest me on shore, I thought I would sail
about a little and see the watery part of the
mobyDick = &Call me Ishmael. Some years ago -- never mind how long precisely -- having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world...&;
run: mobyDick
Block strings can be used to hold formatted or indentation-sensitive text (or, if you just don't feel like escaping quotes and apostrophes). The indentation level that begins the block is maintained throughout, so you can keep it all
aligned with the body of your code.
html = &&&
cup of coffeescript
html = &&strong&\n
cup of coffeescript\n&/strong&&;
Double-quoted block strings, like other double-quoted strings, allow interpolation.
Sometimes you'd like to pass a block comment through to the generated JavaScript. For example, when you need to embed a licensing header at the top of a file. Block comments, which mirror the syntax for block strings, are preserved in
the generated code.
Similar to block strings and comments, CoffeeScript supports block regexes — extended regular expressions that ignore internal whitespace and can contain comments and interpolation. Modeled after Perl's&/x&modifier,
CoffeeSctipt's block regexes are delimited by&///&and
go a long way towards making complex regular expressions readable. To quote from the CoffeeScript source:
OPERATOR = /// ^ (
| [-+*/%&&&|^!?=]=
compound assign / compare
zero-fill right shift
| ([-+:])\1
| ([&|&&])\2=?
logic / shift
soak access
range or splat
var OPERATOR;
OPERATOR = /^(?:[-=]&|[-+*\/%&&&|^!?=]=|&&&=?|([-+:])\1|([&|&&])\2=?|\?\.|\.{2,3})/;
Cake, and Cakefiles
CoffeeScript includes a (very) simple build system similar to&&and&. Naturally, it's
called Cake, and is used for the tasks that build and test the CoffeeScript language itself. Tasks are defined in a file named&Cakefile,
and can be invoked by running&cake
[task]from within the directory. To print a list of all the tasks and options, just type&cake.
Task definitions are written in CoffeeScript, so you can put arbitrary code in your Cakefile. Define a task with a name, a long description, and the function to invoke when the task is run. If your task takes a command-line option, you
can define the option with short and long flags, and it will be made available in the&options&object.
Here's a task that uses the Node.js API to rebuild CoffeeScript's parser:
fs = require 'fs'
option '-o', '--output [DIR]', 'directory for compiled code'
task 'build:parser', 'rebuild the Jison parser', (options) -&
require 'jison'
code = require('./lib/grammar').parser.generate()
= options.output or 'lib'
fs.writeFile &#{dir}/parser.js&, code
fs = require('fs');
option('-o', '--output [DIR]', 'directory for compiled code');
task('build:parser', 'rebuild the Jison parser', function(options) {
require('jison');
code = require('./lib/grammar').parser.generate();
dir = options.output || 'lib';
return fs.writeFile(&& + dir + &/parser.js&, code);
If you need to invoke one task before another — for example, running&build&before&test,
you can use the&invoke&function:&invoke
'build'. Cake tasks are a minimal way to expose your CoffeeScript functions to the command line, so&. If
you need dependencies, or async callbacks, it's best to put them in your code itself — not the cake task.
&text/coffeescript& Script Tags
While it's not recommended for serious use, CoffeeScripts may be included directly within the browser using&&script
type=&text/coffeescript&&&tags. The source includes a compressed and minified version of the compiler ()
as&extras/coffee-script.js.
Include this file on a page with inline CoffeeScript tags, and it will compile and evaluate them in order.
In fact, the little bit of glue script that runs &Try CoffeeScript& above, as well as the jQuery for the menu, is implemented in just this way. View source and look at the bottom of the page to see the example. Including the script also
gives you access to&CoffeeScript.compile()&so
you can pop open Firebug and try compiling some strings.
The usual caveats about CoffeeScript apply — your inline scripts will run within a closure wrapper, so if you want to expose global variables or functions, attach them to the&windowobject.
There are a number of excellent resources to help you get started with CoffeeScript, some of which are freely available online.
&is a brief 5-chapter introduction to CoffeeScript, written with great clarity and precision
by&.&is a reimagination of the excellent book&, as if it had been written in CoffeeScript instead. Covers language features as well a the functional and object oriented programming styles. By&.&is&'s
thorough introduction to the language. By the end of the book, you'll have built a fast-paced multiplayer word game, writing both the client-side and Node.js portions in CoffeeScript.&is a new book by Michael Erasmus that
covers CoffeeScript with an eye towards real-world usage both in the browser (jQuery) and on the server size (Rails, Node).
Screencasts
&is a&&which combines 6 screencasts
with in-browser coding to make learning fun. The first level is free to try out.&is a 75-minute long screencast by&. Highly
memorable for its animations which demonstrate transforming CoffeeScript into the equivalent JS.If you're looking for less of a time commitment, RailsCasts'&&should have you covered, hitting all
of the important notes about CoffeeScript in 11 minutes.
The&&can be found on GitHub. But just to throw out few more:
github's&, a friendly IRC robot that can perform any number of useful and useless tasks.sstephenson's&, a zero-configuration Rack server, with comprehensive annotated source.frank06's&, a Node.js client for&, with support for
HTTP and Protocol Buffers.technoweenie's&, a port of&&for
Node.js.assaf's&, a headless, full-stack, faux-browser testing library for Node.js.jashkenas'&, a port of the&&library
of helper functions.stephank's&, a remake of the Bolo tank game for modern browsers.josh's&, a Node.js-powered&&server.
Use&bin/coffee&to
test your changes,
bin/cake test&to
run the test suite,
bin/cake build&to
rebuild the CoffeeScript compiler, and&
bin/cake build:parser&to
regenerate the Jison parser if you're working on the grammar.&
git checkout lib
&& bin/cake build:full&is a good command to run when you're working on the core language. It'll refresh the lib directory (in case you broke something), build your altered compiler, use that to rebuild itself (a good sanity test) and then run all of the
tests. If they pass, there's a good chance you've made a successful change.
Bug reports, feature proposals, and ideas for changes to the language belong here.
If you'd like to ask a question, the mailing list is a good place to get help.
If you've ever learned a neat CoffeeScript tip or trick, or ran into a gotcha — share it on the wiki. The wiki also serves as a directory of handy&,&, and general&.
Perhaps your CoffeeScript-related question has been asked before. Check the FAQ first.
The CoffeeScript logo is available in Illustrator, EPS and PSD formats, for use in presentations.
Web Chat (IRC)
Quick help and advice can usually be found in the CoffeeScript IRC room. Join&#coffeescript&on&irc.freenode.net,
or click the button below to open a webchat session on this page.
click to open #coffeescript
Change Log
The CoffeeScript compiler now strips Microsoft's UTF-8 BOM if it exists, allowing you to compile BOM-borked source files.Fix Node/compiler deprecation warnings by removing&registerExtension,
and moving from&path.exists&to&fs.exists.Small tweaks to splat compilation, backticks, slicing, and the error for duplicate keys in object literals.
Due to the new semantics of JavaScript's strict mode, CoffeeScript no longer guarantees that constructor functions have names in all runtimes. See&&for
discussion.Inside of a nested function inside of an instance method, it's now possible to call&supermore
reliably (walks recursively up).Named loop variables no longer have different scoping heuristics than other local variables. (Reverts #643)Fix for splats nested within the LHS of destructuring assignment.Corrections to our compile time strict mode forbidding of octal literals.
CoffeeScript now enforces all of JavaScript's&Strict Mode&early syntax errors at compile time. This includes old-style octal literals, duplicate property names in object literals, duplicate parameters
in a function definition, deleting naked variables, setting the value ofeval&or&arguments,
and more. See a full discussion at&.The REPL now has a handy new multi-line mode for entering large blocks of code. It's useful when copy-and-pasting examples into the REPL. Enter multi-line mode with&Ctrl-V.
You may also now pipe input directly into the REPL.CoffeeScript now prints a&Generated
by CoffeeScript VERSION&header at the top of each compiled file.Conditional assignment of previously undefined variables&a
or= b&is now considered a syntax error.A tweak to the semantics of&do,
which can now be used to more easily simulate a namespace:&do
(x = 1, y = 2) -& ...Loop indices are now mutable within a loop iteration, and immutable between them.Both endpoints of a slice are now allowed to be omitted for consistency, effectively creating a shallow copy of the list.Additional tweaks and improvments to&coffee
--watch&under Node's &new& file watching API. Watch will now beep by default if you introduce a syntax error into a watched script. We also now ignore hidden directories by default when watching recursively.
Multiple improvements to&coffee
--watch&and&--join.
You may now use both together, as well as add and remove files and directories within a&--watch'd
folder.The&throw&statement
can now be used as part of an expression.Block comments at the top of the file will now appear outside of the safety closure wrapper.Fixed a number of minor 1.1.3 regressions having to do with trailing operators and unfinished lines, and a more major 1.1.3 regression that caused bound functions&withinbound class functions to have the incorrect&this.
Ahh, whitespace. CoffeeScript's compiled JS now tries to space things out and keep it readable, as you can see in the examples on this page.You can now call&super&in
class level methods in class bodies, and bound class methods now preserve their correct context.JavaScript has always supported octal numbers&010
is 8, and hexadecimal numbers&0xf
is 15, but CoffeeScript now also supports binary numbers:&0b10
is 2.The CoffeeScript module has been nested under a subdirectory to make it easier to&require&individual
components separately, without having to use&npm. For example, after adding the CoffeeScript folder to your path:&require('coffee-script/lexer')There's a new &link& feature in Try CoffeeScript on this webpage. Use it to get a shareable permalink for your example script.The&coffee
--watch&feature now only works on Node.js 0.6.0 and higher, but now also works properly on Windows.Lots of small bug fixes from&,&,&,
Fixes for block comment formatting,&?=&compilation,
implicit calls against control structures, implicit invocation of a try/catch block, variadic arguments leaking from local scope, line numbers in syntax errors following heregexes, property access on parenthesized number literals, bound class methods and super
with reserved names, a REPL overhaul, consecutive compiled semicolons, block comments in implicitly called objects, and a Chrome bug.
Bugfix release for classes with external constructor functions, see issue #1182.
When running via the&coffee&executable,&process.argv&and
friends now report&coffeeinstead
Better compatibility with&Node.js 0.4.x&module lookup changes. The output in the REPL is now colorized, like Node's is. Giving your concatenated CoffeeScripts a name when using&--join&is
now mandatory. Fix for lexing compound division&/=&as
a regex accidentally. All&text/coffeescript&tags
should now execute in the order they're included. Fixed an issue with extended subclasses using external constructor functions. Fixed an edge-case infinite loop in&addImplicitParentheses.
Fixed exponential slowdown with long chains of function calls. Globals no longer leak into the CoffeeScript REPL. Splatted parameters are declared local to the function.
Fixed a lexer bug with Unicode identifiers. Updated REPL for compatibility with Node.js 0.3.7. Fixed requiring relative paths in the REPL. Trailing&return&and&return
undefined&are now optimized away. Stopped requiring the core Node.js&&util&&module
for back-compatibility with Node.js 0.2.5. Fixed a case where a conditional&return&would
cause fallthrough in a&switch&statement.
Optimized empty objects in destructuring assignment.
CoffeeScript loops no longer try to preserve block scope when functions are being generated within the loop body. Instead, you can use the&do&keyword
to create a convenient closure wrapper. Added a&--nodejs&flag
for passing through options directly to the&node&executable.
Better behavior around the use of pure statements within expressions. Fixed inclusive slicing through&-1,
for all browsers, and splicing with arbitrary expressions as endpoints.
The REPL now properly formats stacktraces, and stays alive through asynchronous exceptions. Using&--watch&now
prints timestamps as files are compiled. Fixed some accidentally-leaking variables within plucked closure-loops. Constructors now maintain their declaration location within a class body. Dynamic object keys were removed. Nested classes are now supported. Fixes
execution context for naked splatted functions. Bugfix for inversion of chained comparisons. Chained class instantiation now works properly with splats.
0.9.5 should be considered the first release candidate for CoffeeScript 1.0. There have been a large number of internal changes since the previous release, many contributed from&satyr's&&dialect
of CoffeeScript. Heregexes (extended regexes) were added. Functions can now have default arguments. Class bodies are now executable code. Improved syntax errors for invalid CoffeeScript.&undefined&now
works like&null,
and cannot be assigned a new value. There was a precedence change with respect to single-line comprehensions:&result
= i for i in list
used to parse as&result
= (i for i in list)&by default ... it now parses as&
(result = i) for
i in list.
CoffeeScript now uses appropriately-named temporary variables, and recycles their references after use. Added&require.extensions&support
for&Node.js 0.3. Loading CoffeeScript in the browser now adds just a single&CoffeeScript&object
to global scope. Fixes for implicit object and block comment edge cases.
CoffeeScript&switch&statements
now compile into JS&switch&statements
— they previously compiled into&if/else&chains
for JavaScript 1.3 compatibility. Soaking a function invocation is now supported. Users of the RubyMine editor should now be able to use&--watch&mode.
Specifying the start and end of a range literal is now optional, eg.&array[3..].
You can now say&a
not instanceof b. Fixed important bugs with nested significant and non-significant indentation (Issue #637). Added a&--require&flag
that allows you to hook into the&coffeecommand.
Added a custom&jsl.conf&file
for our preferred JavaScriptLint setup. Sped up Jison grammar compilation time by flattening rules for operations. Block comments can now be used with JavaScript-minifier-friendly syntax. Added JavaScript's compound assignment bitwise operators. Bugfixes to
implicit object literals with leading number and string keys, as the subject of implicit calls, and as part of compound assignment.
Bugfix release for&0.9.1. Greatly improves the handling of mixed implicit objects, implicit function calls, and implicit indentation. String and regex interpolation is now strictly&#{
... }&(Ruby style). The compiler now takes a&--require&flag,
which specifies scripts to run before compilation.
The CoffeeScript&0.9&series is considered to be a release candidate for&1.0; let's give her a shakedown cruise.&0.9.0&introduces a massive backwards-incompatible change: Assignment
now uses&=,
and object literals use&:,
as in JavaScript. This allows us to have implicit object literals, and YAML-style object definitions. Half assignments are removed, in favor of&+=,&or=,
and friends. Interpolation now uses a hash mark&#&instead
of the dollar sign&$&—
because dollar signs may be part of a valid JS identifier. Downwards range comprehensions are now safe again, and are optimized to straight for loops when created with integer endpoints. A fast, unguarded form of object comprehension was added:for
all key, value of object. Mentioning the&super&keyword
with no arguments now forwards all arguments passed to the function, as in Ruby. If you extend class&B&from
parent class&A,
an&extended&method
defined, it will be called, passing in&B&—
this enables static inheritance, among other things. Cleaner output for functions bound with the fat arrow.&@variables&can
now be used in parameter lists, with the parameter being automatically set as a property on the object — useful in constructors and setter functions. Constructor functions can now take splats.
Quick bugfix (right after 0.7.1) for a problem that prevented&coffee&command-line
options from being parsed in some circumstances.
Block-style comments are now passed through and printed as JavaScript block comments -- making them useful for licenses and copyright headers. Better support for running coffee scripts standalone via hashbangs. Improved syntax
errors for tokens that are not in the grammar.
Official CoffeeScript variable style is now camelCase, as in JavaScript. Reserved words are now allowed as object keys, and will be quoted for you. Range comprehensions now generate cleaner code, but you have to specify&by
-1&if you'd like to iterate downward. Reporting of syntax errors is greatly improved from the previous release. Running&coffeewith
no arguments now launches the REPL, with Readline support. The&&-&bind
operator has been removed from CoffeeScript. The&loop&keyword
was added, which is equivalent to a&while
true&loop. Comprehensions that contain closures will now close over their variables, like the semantics of a&forEach.
You can now use bound function in class definitions (bound to the instance). For consistency,&a
in b&is now an array presence check, and&a
of b&is an object-key check. Comments are no longer passed through to the generated JavaScript.
The&coffee&command
will now preserve directory structure when compiling a directory full of scripts. Fixed two omissions that were preventing the CoffeeScript compiler from running live within Internet Explorer. There's now a syntax for block comments, similar in spirit to CoffeeScript's
heredocs. ECMA Harmony DRY-style pattern matching is now supported, where the name of the property is the same as the name of the value:&{name,
length}: func. Pattern matching is now allowed within comprehension variables.&unless&is
now allowed in block form.&until&loops
were added, as the inverse of&whileloops.&switch&statements
are now allowed without switch object clauses. Compatible with Node.js&v0.1.95.
Upgraded CoffeeScript for compatibility with the new Node.js&v0.1.90&series.
Trailing commas are now allowed, a-la Python. Static properties may be assigned directly within class definitions, using&@property&notation.
Interpolation can now be used within regular expressions and heredocs, as well as strings. Added the&&-&bind
operator. Allowing assignment to half-expressions instead of special&||=-style
operators. The arguments object is no longer automatically converted into an array. After requiring&coffee-script,
Node.js can now directly load&.coffee&files,
thanks toregisterExtension. Multiple splats can now be used in function calls, arrays, and pattern matching.
String interpolation, contributed by&. Since&--run&has
been the default since0.5.3, updating&--stdio&and&--eval&to
run by default, pass&--compile&as
well if you'd like to print the result.
Bugfix that corrects the Node.js global constants&__filename&and&__dirname.
Tweaks for more flexible parsing of nested function literals and improperly-indented comments. Updates for the latest Node.js API.
CoffeeScript now has a syntax for defining classes. Many of the core components (Nodes, Lexer, Rewriter, Scope, Optparse) are using them. Cakefiles can use&optparse.coffee&to
define options for tasks.&--run&is
now the default flag for the&coffee&command,
use&--compile&to
save JavaScripts. Bugfix for an ambiguity between RegExp literals and chained divisions.
Added a compressed version of the compiler for inclusion in web pages as&
extras/coffee-script.js.
It'll automatically run any script tags with type&text/coffeescriptfor
you. Added a&--stdio&option
to the&coffee&command,
for piped-in compiles.
Improvements to null soaking with the existential operator, including soaks on indexed properties. Added conditions to&while&loops,
so you can use them as filters with&when,
in the same manner as comprehensions.
CoffeeScript 0.5.0 is a major release, While there are no language changes, the Ruby compiler has been removed in favor of a self-hosting compiler written in pure CoffeeScript.
@property&is
now a shorthand for&this.property.
Switched the default JavaScript engine from Narwhal to Node.js. Pass the&--narwhal&flag
if you'd like to continue using it.
CoffeeScript 0.3 includes major syntax changes:&
The function symbol was changed to&-&,
and the bound function symbol is now&=&.&
Parameter lists in function definitions must now be wrapped in parentheses.&
Added property soaking, with the&?.&operator.&
Made parentheses optional, when invoking functions with arguments.&
Removed the obsolete block literal syntax.
Added Python-style chained comparisons, the conditional existence operator&?=,
and some examples from&Beautiful Code. Bugfixes relating to statement-to-expression conversion, arguments-to-array conversion, and the TextMate syntax highlighter.
The conditions in switch statements can now take multiple values at once — If any of them are true, the case will run. Added the long arrow&==&,
which defines and immediately binds a function to&this.
While loops can now be used as expressions, in the same way that comprehensions can. Splats can be used within pattern matches to soak up the rest of an array.
Added ECMAScript Harmony style destructuring assignment, for dealing with extracting values from nested arrays and objects. Added indentation-sensitive heredocs for nicely formatted strings or chunks of code.
Axed the unsatisfactory&ino&keyword,
replacing it with&of&for
object comprehensions. They now look like:&for
prop, value of object.
When performing a comprehension over an object, use&ino,
instead of&in,
which helps us generate smaller, more efficient code at compile time.&
Added&::&as
a shorthand for saying&.prototype.&
The &splat& symbol has been changed from a prefix asterisk&*,
to a postfix ellipsis&...&
Added JavaScript's&in&operator,
empty&return&statements,
and empty&while&loops.&
Constructor functions that start with capital letters now include a safety check to make sure that the new instance of the object is returned.&
The&extends&keyword
now functions identically to&goog.inherits&in
Google's Closure Library.
Arguments objects are now converted into real arrays when referenced.
Major release. Significant whitespace. Better statement-to-expression conversion. Splats. Splice literals. Object comprehensions. Blocks. The existential operator. Many thanks to all the folks who posted issues, with special thanks
to&&for whitespace and expression help.
Bugfix for running&coffee
--interactive&and&--run&from
outside of the CoffeeScript directory. Bugfix for nested function/if-statements.
Array slice literals and array comprehensions can now both take Ruby-style ranges to specify the start and end. JavaScript variable declaration is now pushed up to the top of the scope, making all assignment statements into expressions.
You can use&\&to
escape newlines. The&coffee-script&command
is now called&coffee.
The official CoffeeScript extension is now&.coffee&instead
of&.cs, which
properly belongs to&. Due to popular demand, you can now also use&=&to
assign. Unlike JavaScript,&=&can
also be used within object literals, interchangeably with&:.
Made a grammatical fix for chained function calls like&func(1)(2)(3)(4).
Inheritance and super no longer use__proto__,
so they should be IE-compatible now.
The&coffee&command
now includes&--interactive,
which launches an interactive CoffeeScript session, and&--run,
which directly compiles and executes a script. Both options depend on a working installation of Narwhal. The&aint&keyword
has been replaced by&isnt,
which goes together a little smoother with&is.
Quoted strings are now allowed as identifiers within object literals: eg.&{&5+5&:
10}. All assignment operators now use a colon:&+:,&-:,&*:,
Fixed a bug with calling&super()&through
more than one level of inheritance, with the re-addition of the&extends&keyword.
Added experimental&&support (as a Tusk package), contributed by&, including&bin/cs&as a CoffeeScript
REPL and interpreter. New&--no-wrap&option
to suppress the safety function wrapper.
Added&instanceof&and&typeof&as
operators.
Initial CoffeeScript release.
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