Simplest way for leading zero padding in JavaScript

number-pad-zero.js

Number.prototype.pad = function(size) {
  var s = String(this);
  while (s.length < (size || 2)) {s = "0" + s;}
  return s;
}

(1).pad(3) // => "001"
(10).pad(3) // => "010"
(100).pad(3) // => "100"

A stitch in time saves nine. Thanks

@SynCap:

pz(-100, 4);   // '-100'
pz(-100, 5);   // '-00100'

@n3y: thnx

now:

> pz(-100, 4)
"-0100"
> pz(-100, 5)
"-00100"
> pz(-100, 3)
"-100"
> pz(-100, 2)
"-100"

@SynCap
the repeat function isn't supported by IE < Version 12 (Edge)

I'm looking for something that works with decimals, eg. 4.5 -> 004.5 or 4.543 -> 004.543

Thanks!

Number.prototype.pad = function(size) {
    var s = String(this);
    var getsize = ()=>{ var j = 0, fc = false; for(var i=0; i<s.length; i++){ if(!fc){if(s.charAt(i) == '.'){ fc = true; }else{ j++; }}} return j; };
    //console.log(getsize());
    while (getsize() < (size || 2)) {s = "0" + s;}
    return s;
}

applied fix to prevent decimal count on float type

"str".split("").fill("*", 0, -1).join("")
This is useful if you want to mask a string

padStart() for the win!

Only without IE

zeroPad(number) {
    return number > 9 ? number : '0' + number;
 }

Wow, Thank you. How can I export this function & Import it to use it in other files?