UnderscoreJS - For loop the length of an array

Question

Say I have an array myArray of some length N. I want to loop Nth time. In pure Javascript, that would be:

for (var i = 0; i < myArray.length; i++) {}

Is there a way to also do this in UnderscoreJS? I know I can use _.each in the following way:

_.each(myArray, function(a) {
});

but I don't particularly want to loop through the entries. There is no reason why i want to do this. This is purely a thought experiment and I was just wondering if there is a way of doing this!

What's wrong with _.each? Doesn't it call the function N times? — univerio
– univerio, Commented Aug 16, 2014 at 20:31
There is nothing wrong with _.each. It does run N times. But I was just wondering if I could create the exact same thing as the for loop in Javascript (i.e. just loop with the index, not the actual item). — Kousha
– Kousha, Commented Aug 16, 2014 at 20:32
@univerio: That's pretty close to an answer. A documentation reference, some explanation, and maybe an example is all it needs. — mu is too short
– mu is too short, Commented Aug 16, 2014 at 20:41
@univerio, this works perfectly. If you post it, I can vote it. — Kousha
– Kousha, Commented Aug 16, 2014 at 20:42

univerio · Accepted Answer · 2014-08-17 01:59:21Z

2

You can use the _.times() function to execute a callback n times:

_.times(myArray.length, function(i) {...})

answered Aug 17, 2014 at 1:59

univerio

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Mark Reed · Accepted Answer · 2014-08-17 02:26:52Z

0

Note that you can use each and just use the index and ignore the actual entries:

_.each(myArray, function(a, i) {
   ... do something with i but not a ...
}

answered Aug 17, 2014 at 2:26

Mark Reed

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2 Comments

Kousha Over a year ago

Thanks but as I said, I know I can do that. I was looking to see if there is a way only get the index. Please see the accepted the answer to what I was looking for.

Mark Reed Over a year ago

It wasn't clear that you knew about the iterator function getting the index as a second argument, since you didn't have such an argument in your example code. That's the part I was trying to get across in case you weren't aware of it and thought you would have to keep your own counter or something, which might influence your desire not to go that route.

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