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

You could take a counter and decrement it.

var string = '07/12/2017  11:01 AM             21523 filename with s p a c  e  s.js',
    n = 4,
    result = string.replace(/\s+/g, s => n ? (n--, '|') : s);
    
console.log(result);

You could replace the ternary expression with one with logical AND and OR.

var string = '07/12/2017  11:01 AM             21523 filename with s p a c  e  s.js',
    n = 4,
    result = string.replace(/\s+/g, s => n && n-- && '|' || s);
    
console.log(result);