Vanilla Javascript number padding functions

README.MD

Disadvantages of String.padStart()

• works only in modern browsers and environments;
• don't care about negative
• works only on String primitives not a Number

> (-4+'').padStart(7,'0')
"00000-4"

> (400.302).padStart(9, '0')
Uncaught TypeError: 400.302.padStart is not a function at <anonymous>:1:11

(0005).padStart(3, '0')
Uncaught TypeError: 5.padStart is not a function at <anonymous>:1:8

Features:

• cares about negative numbers
• cares about length -- don't cut just pads
• works with Numbers
• v2 works in legacy trash cans even in MS IE 3.1 and Rhino
• have a short way (defaults)

padNums.js

/** ES2015+ -- ultra-fast
 * @param n <Number> what to pad left with
 * @param z <Number> (zeros :) ) width which pad to
 * @param s <String> (sign :) ) char to pad with, of course may be some like that 'oO'
 * @return <String>
 * @example
 * 	pz(7, 15, 'oO')
 * 	// ==> "oOoOoOoOoOoOoO7"
 * 
 * 	pz(-1005007, 20)
 * 	// ==> "-00000000000001005007"
*/
const pn = (n, z = 2, s= '0') =>
	(n+'').length <= z ? (['','-'])[+(n<0)] + (s.repeat(z) + Math.abs(n)).slice(-1*z) : n + '';

// ** Legaacy version do the same but can work in carton boxes **
function pn_legacy(n, z, s) {
	var z= z || 2, s = s || '0';
	return (n+'').length <= z ? (['','-'])[+(n<0)] + (s.repeat(z) + Math.abs(n)).slice(-1*z) : n + '';
}