I want to type something like [1] * totalPoints so that if totalPoints was 3, it would give me an array of [1,1,1]. I can't think of what it would be called though.. as such, my searches have turned up nothing. I mean, I could easily accomplish this with a for loop, but I seem to be under the impression that I've used something like this before and I just can't think of it.
Is there anything like this in javascript?
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I don't think JS has this built-in, you may be thinking of other languages.Barmar– Barmar2014-03-01 00:33:59 +00:00Commented Mar 1, 2014 at 0:33
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This has been asked before: stackoverflow.com/questions/4049847/…user3358344– user33583442014-03-01 00:34:58 +00:00Commented Mar 1, 2014 at 0:34
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possible duplicate of Create an array with same element repeated multiple times in javascriptBarmar– Barmar2014-03-01 00:35:55 +00:00Commented Mar 1, 2014 at 0:35
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Alright, thanks. I know how I'm going to handle it now. It was probably python I did that in now that I think about it...さりげない告白– さりげない告白2014-03-01 00:39:00 +00:00Commented Mar 1, 2014 at 0:39
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2 Answers
Create a new array of size 3 then use the array map function on each element, calling valueOf:
var totalPoints = Array.apply(null, new Array(3)).map(Number.prototype.valueOf,1);
7 Comments
さりげない告白
This is the closest to what I was looking for. totalPoints was the variable however, so it would go where the 3 is and the array would be named something else. Thanks for your answer. ^^
Ingo Bürk
Though this is nifty code, I would recommend against it. Really what's the reason to save those few lines of a loop but in return making a task as simple as this look so complicated? Anyone looking at this code will have trouble understanding what it does, including you in a few weeks (if you even understand how this works in the first place). Readability is more important than saving yourself a couple of lines.
@IngoBürk and is the slowest option. A pre-allocated array filled with a for-loop is by far the fastest option (jsperf.com/pre-fill-an-array)
Ingo Bürk
@Ken But that also doesn't matter. If you have to worry about the performance of creating an array with a few entries, you are in a lot of trouble.
user13500
@IngoBürk: That all depends on context. Try playing with canvas for example. Every bit counts.
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var myArray = [];
function pointsArray(totalPoints) {
for (i = 0; i < totalPoints; i++) {
myArray.push(1);
}
return myArray;
}
