Split a string, at every nth position, with JavaScript?

Question

I have the following string:

foofaafoofaafoofaafoofaafoofaa

An array with 10 rows (if I split by every 3rd character, that is), which looks something like this, if I were to instantiate it:

var fooarray = new Array ('foo', 'faa', 'foo', 'faa', 'foo', 'faa', 'foo', 'faa', 'foo', 'faa');

So I want a function, either built-in or custom-made, which can help me split up a string by every nth character.

There's an answer here that does just that (http://stackoverflow.com/questions/4017671/how-do-you-split-a-string-at-certain-character-numbers-in-javascript) — Mark Walters, Oct 02 '12 at 08:25

score 85 · Accepted Answer · edited Jan 03 '17 at 18:43

85

Try the below code:

var foo = "foofaafoofaafoofaafoofaafoofaa";
console.log( foo.match(/.{1,3}/g) );

For nth position:

foo.match(new RegExp('.{1,' + n + '}', 'g'));

edited Jan 03 '17 at 18:43

vsync

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answered Oct 02 '12 at 08:25

xdazz

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@xdazz But the OP said every nth position; your regex is fixed at 3. Generalize it for an upvote. :) – Ray Toal Oct 02 '12 at 08:29
Can you split it using regex but from right to left? – vsync Sep 15 '16 at 08:21
2

@vsync: I don't know if that's possible in the *general* case, but maybe you could just reverse the input string, do the matches, then reverse the output? – damd Jan 03 '17 at 15:14
bravo my friend that is a very nice use of regex – SimonC Jun 04 '21 at 12:52

score 12 · Answer 2 · edited Jan 03 '17 at 18:45

12

var s = "foofaafoofaafoofaafoofaafoofaa";
var a = [];
var i = 3;

do{ a.push(s.substring(0, i)) } 
while( (s = s.substring(i, s.length)) != "" );

console.log( a )

Prints:

foo,faa,foo,faa,foo,faa,foo,faa,foo,faa

Working demo: http://jsfiddle.net/9RXTW/

edited Jan 03 '17 at 18:45

vsync

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answered Oct 02 '12 at 08:27

sp00m

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freefaller · Answer 3 · 2022-01-02T15:28:58.057

7

As I was writing this, @xdazz came up with the wonderfully simple regex solution.

But as you have asked (on the comments to that answer) for a non-regex solution, I will submit this anyway...

function splitNChars(txt, num) {
  var result = [];
  for (var i = 0; i < txt.length; i += num) {
    result.push(txt.substr(i, num));
  }
  return result;
}
console.log(splitNChars("foofaafoofaafoofaafoofaafoofaa",3));

edited Jan 02 '22 at 15:28

answered Oct 02 '12 at 08:27

freefaller

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Also `array` doesnt make a good variable name. Even thought Javascript is case sensitive it might be confusing. – clentfort Oct 02 '12 at 08:30

score 4 · Answer 4 · answered Oct 02 '12 at 08:29

4

You can do like this:

var input = "foofaafoofaafoofaafoofaafoofaa";

var result = [];
while (input.length) {
    result.push(input.substr(0, 3));
    input = input.substr(3);
}

Demo: http://jsfiddle.net/Guffa/yAZJ2/

answered Oct 02 '12 at 08:29

Guffa

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score 1 · Answer 5 · edited May 23 '17 at 12:32

1

As Mark Walter has pointed out, this solution from another Stack Overflow question works perfectly:

function splitStringAtInterval (string, interval) {
  var result = [];
  for (var i=0; i<string.length; i+=interval)
    result.push(string.substring (i, i+interval));
  return result;
}

edited May 23 '17 at 12:32

Community

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answered Oct 02 '12 at 08:30

Lucas

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score 0 · Answer 6 · answered Oct 02 '12 at 08:33

The function followed by an example using it. The example test outputs: ["abc","def","ghi","j"]

function splitEvery(str, n)
{
    var arr = new Array;
    for (var i = 0; i < str.length; i += n)
    {
        arr.push(str.substr(i, n));
    }
    return arr;
}

var result = splitEvery('abcdefghij', 3);
document.write(JSON.stringify(result));

Split a string, at every nth position, with JavaScript?

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