JavaScript到CoffeeScript错误

Question

I have a function that toggles all of the others checkboxes when the last checkbox is clicked.

It works perfectly in ordinary JavaScript:

$(document).ready(function() {
  $('#manage').click(function(event) {   
      if(this.checked) {
          $('.checkbox:checkbox').each(function() {
              this.checked = true;                        
          });
      }
      if(!this.checked) {
          $('.checkbox:checkbox').each(function() {
              this.checked = false;                        
          });
      }
  });
});

http://jsfiddle.net/PauaN/9/

However when I compile into CoffeeScript (using http://js2coffee.org/ ) the functionality breaks when the checkboxes are toggled off:

$(document).ready ->
  $("#manage").click (event) ->
    if @checked
      $(".checkbox:checkbox").each ->
        @checked = true

    unless @checked
      $(".checkbox:checkbox").each ->
        @checked = false

http://jsfiddle.net/FRs5d/7/

I think this is because the second each loop is only running once.

What's going wrong?

Answer 1

The problem is the following. In the converted script the implicit return created by CoffeeScript is false

unless @checked
  $(".checkbox:checkbox").each () ->
    @checked = false
    # here false is returned stopping the each function from continuing

so the solution is adding true at the end of the function

unless @checked
  $(".checkbox:checkbox").each () ->
    @checked = false
    true

This fiddle shows it in action.

Answer 2

Two things happens:

1. Coffee Script puts return at end of every function, so @checked = true changes into return this.checked = true;
2. If function in Jquery each() returns false , it does not continue.

What will solve this, is changing your last line

@checked = false

to something like this:

@checked = false
return true