array = [1,2,3,4]
for num in array
//do something
What is the value of num in the context of the rest of the function? Does num get scoped to the loop?
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What happened when you ran it?user541686– user5416862012-05-30 06:10:51 +00:00Commented May 30, 2012 at 6:10
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You can try CoffeeScript stuff and see the compiled result here =Depidemian– epidemian2012-05-30 07:28:01 +00:00Commented May 30, 2012 at 7:28
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1 Answer
No, num doesn't get scoped to the loop. As you can see in compiled JS (as @epidemian pointed out) it is current scope variable, so you can access it also in the rest of the function (e.g. rest of the current scope).
But be careful in case of defining function callback inside the loop:
array = [1, 2, 3]
for num in array
setTimeout (() -> console.log num), 1
outputs
3
3
3
To capture current variable inside the callback, you should use do which simply calls the function:
for num in array
do (num) ->
setTimeout (() -> console.log num), 1
2 Comments
wmarbut
I've created some delightful race conditions with this mistake, be weary
ndbroadbent
Just got bit by this, too. I feel like
do (num) -> should be the default behaviour.