Split large string in n-size chunks in JavaScript

Question

I would like to split a very large string (let's say, 10,000 characters) into N-size chunks.

What would be the best way in terms of performance to do this?

For instance: "1234567890" split by 2 would become ["12", "34", "56", "78", "90"].

Would something like this be possible using String.prototype.match and if so, would that be the best way to do it in terms of performance?

Answer 1

You can do something like this:

"1234567890".match(/.{1,2}/g);
// Results in:
["12", "34", "56", "78", "90"]

The method will still work with strings whose size is not an exact multiple of the chunk-size:

"123456789".match(/.{1,2}/g);
// Results in:
["12", "34", "56", "78", "9"]

In general, for any string out of which you want to extract at-most n-sized substrings, you would do:

str.match(/.{1,n}/g); // Replace n with the size of the substring

If your string can contain newlines or carriage returns, you would do:

str.match(/(.|[\r\n]){1,n}/g); // Replace n with the size of the substring

As far as performance, I tried this out with approximately 10k characters and it took a little over a second on Chrome. YMMV.

This can also be used in a reusable function:

function chunkString(str, length) {
  return str.match(new RegExp('.{1,' + length + '}', 'g'));
}