Replace First N Occurrences in the String

Question

How can I replace first N occurrences of many whitespaces and tabs in the following string:

07/12/2017  11:01 AM             21523 filename with         


        

Answer 1

Some answers here are really good already, but since you say you want speed, I'd go with a single while, like this:

var logLine = '07/12/2017  11:01 AM             21523 filename with s p a c  e  s.js';
var N = 4;
while(--N + 1){
  logLine = logLine.replace(/\s+/, '|');
}
console.log(logLine);

Here's on JSFiddle: https://jsfiddle.net/2bxpygjr/