胖箭重复？

Question

When I'm writing coffee script I tend to do this an awful lot (pseudo code):

$link.click (e) =>
  this._clicked(e)

Is there really not some way to bind transparently in CoffeeScript? I'd like to be able to do:

$link.click =this._clicked

or something, which would bind my this._clicked method, directly to the event, keeping its this pointer

any ideas?

update

_clicked would be defined as:

_clicked: (e) ->
  # some code

Answer 1

Nothing special with coffeescript. Just do

$link.click @_clicked

And then define _clicked as

_clicked: (e) =>
  # some code

It'll pass this._clicked as the handler for the click event of link .

You can pass any function as callbacks like this. The keypoint is to not execute the function (there are no () in @_clicked ). A function in JS is a normal variable, which can be passed around as parameters to other functions.

With

$link.click ->

youre just passing a function to .click directly without storing it into a variable.

To keep the this you either define @_clicked with a fat arrow or you use JavaScripts bind function which returns a function where this is bound to a certain value.

CoffeeScript is not adding any extra functionality to JavaScript. The Fat arrow just does a bind similar to the bind function from the link (if its used in a method definition of a class) or just does the var _this = this trick when a function is defined inside a function.