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I have a one-dimensional array of strings in Javascript that I'd like to turn into a comma-separated list. Is there a simple way in garden-variety Javascript (or jQuery) to turn that into a comma-separated list? (I know how to iterate through the array and build the string myself by concatenation if that's the only way.)

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3 Answers

up vote 120 down vote accepted

The join function:

var arr = new Array(3);
arr[0] = "Zero";
arr[1] = "One";
arr[2] = "Two";

document.write(arr.join(","));
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13  
Noooooooooo! Tempted to downvote. What if the strings contain commas?! They need to be quoted. – Mark Dec 2 '11 at 16:19
2  
@davewilliams459: But you're not the OP? Op said "a one-dimensional array of strings". Strings. Not IDs. That implies they could be anything. Which means they may contain other commas. – Mark Feb 8 '12 at 16:26
3  
@Mark: The answer is correct for the question as asked. Any other requirements are left to the individual to work out for themselves. OP asked for a comma-separated list, not a quoted CSV-type format. – Wayne Feb 10 '12 at 22:37
4  
@Wayne: I still think a warning is in order :) People don't always think these things through, and then they shoot themselves in the foot later. – Mark Feb 10 '12 at 22:54
1  
@Mark - your comment is perfectly valid (as others have indicated with an upvote) but more helpful might have been to actually provide the alternative answer with example code? – Chris Jul 8 '12 at 10:06
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up vote 18 down vote

Or (more efficiently):

var arr = new Array(3);
arr[0] = "Zero";
arr[1] = "One";
arr[2] = "Two";

document.write(arr); // same as document.write(arr.toString()) in this context

The toString method of an array when called returns exactly what you need - comma-separated list.

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In most cases, toString is actually slower than array join. Lookie here: jsperf.com/tostring-join – Sameer Alibhai Jul 9 at 19:10
up vote 17 down vote

Actually, the toString() implementation does a join with commas by default:

var arr = [ 42, 55 ];
var str1 = arr.toString(); // Gives you "42,55"
var str2 = String(arr); // Ditto

I don't know if this is mandated by the JS spec but this is what most pretty much all browsers seem to be doing.

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1  
array join is faster jsperf.com/tostring-join – Sameer Alibhai Jul 9 at 19:12

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