How can I define event handlers inside a loop using the loop variable?

Question

for a in [1,2,3]
  $('body').click (x) =>
    alert a

It alerts 3 three times when I click the body. I would like it to alert 1, 2, and 3.

I would like to click the body once and have three alerts pop up, the first with 1, second with 2, third with 3. — Loren
– Loren, Commented Oct 19, 2011 at 2:20

Brian Genisio · Accepted Answer · 2011-10-19 02:35:39Z

5

I screwed up the syntax the first time, but got it right this time:

You need to create a closure around the function and call it immediately (much like you would in Javascript). Coffeescript even gives you a nice syntax to do that for you... the do keyword:

for a in [1,2,3]
  do (a) ->
    $('body').click (x) =>
      alert a

answered Oct 19, 2011 at 2:35

Brian Genisio

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1 Comment

Trevor Burnham Over a year ago

+1. See my PragPub article, A CoffeeScript Intervention, for elaboration on how this works.

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