aseemk/coffeescript-updates.md

## coffeescript-updates.md

      
        

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              coffeescript-updates.md
            
          
        
      
      
    CoffeeScript 1.7 is shaping up to be a pretty kick-ass release with significant improvements. Here are the ones I'm most excited about, in order of my own excitement.
Parentheses-free chaining
https://github.com/jashkenas/coffee-script/pull/3263
Years of being wished for, finally granted!
result = range 1, 3
  .concat range 4, 6
  .map (x) -> x * x
  .filter (x) -> x % 2 is 0

console.log result # [4, 16, 36]
$ 'body'
.click (e) ->
  $ '.box'
  .fadeIn 'fast'
  .addClass '.active'
  .css 'marginRight', '10px'
Proper multiline strings
These two both solve roughly the same problem:
https://github.com/jashkenas/coffee-script/pull/3246 

https://github.com/jashkenas/coffee-script/pull/3256
These'll finally let you wrap long strings (e.g. user-facing messages) without breaking your code's indentation, or manually stripping newlines out. I've been wanting these for so long!
if true
  if not false
    console.log 'Hello world.
      This is a long line of text
      that I’d like split in my code.'

# equivalent to:

if true
  if not false
    console.log 'Hello world. This is a long line of text that I’d like split in my code.'
console.log '''
  By default, prefixed CSS will rewrite original files.
  If you didn't set input files, autoprefixer will \
    read from stdin stream.
  Output CSS will be written to stdout stream on \
    `-o -' argument or stdin input.
'''

# equivalent to:

desc = '''
  By default, prefixed CSS will rewrite original files.
  If you didn't set input files, autoprefixer will read from stdin stream.
  Output CSS will be written to stdout stream on `-o -' argument or stdin input.
'''
Expansion in array destructuring
https://github.com/jashkenas/coffee-script/pull/3268
The name sounds confusing, but this is straightforward:
# to get the first and last, what you have to do today:
[first, middle..., last] = array

# what you can do now:
[first, ..., last] = array
But here's the killer use for it:
# what you have to do today to get the last element in an array:
last = array[array.length - 1]

# or if you, like me, like to use features to their fullest:
[last] = array[-1..]

# what you can do now:
[..., last] = array
New mathematical operators
https://github.com/jashkenas/coffee-script/pull/2887

Power operator **
Floor division operator //
Correct modulo operator %% (respects negatives)

I remember wishing for each one of these when I worked on Seadragon Ajax!
Whitespace escaping in heregexes
https://github.com/jashkenas/coffee-script/pull/3214
Not a huge deal to most people, but I've frequently wondered about this.
regex = /// <link\ href="#{URL}" ///
Proper require.extensions registration
https://github.com/jashkenas/coffee-script/pull/3279
Like Streamline.js and others, extending Node's require() to automatically compile CoffeeScript files is now an explicit action. This now prevents versioning conflicts, etc. with nested local CoffeeScript dependencies.
# if you're working with the compiler programmatically:
CoffeeScript = require 'coffee-script'
CoffeeScript.register()

# or, e.g. for Mocha configuration
require 'coffee-script/register'
coffee <dir> executes index.coffee now
https://github.com/jashkenas/coffee-script/pull/3292
Like the title says. This brings the coffee executable closer in line with node. There's still a little room for improvement (e.g. if your main file is named app.coffee), but this is already a great step forward.
Credits
Phew! Talk about a powerful list.
My undying gratitute to the contributors of the above pull requests. A special shout-out to @xixixao in particular for contributing about half of them!  Thank you all very, very much.
Looking forward to CoffeeScript 1.7!