Javascript String padLeft(ch, n)

String.prototype.padLeft = function(ch, n) {
  return this.length >= n
    ? this.valueOf()/*from   w w w.  ja va2 s . c  o m*/
    : (Array(n + 1).join(ch) + this).slice(-n);
};

/*//w  ww . j  a  v  a 2  s .  c  om
You have to write two functions, padLeft and padRight that will fill the missing characters so the other system can import the data without any errors.

Registry Number   | Activity Code
00000000001337    | 1337000
60316817000448    | 6204000
*/

'use strict';

String.prototype.padLeft = function(ch, n) {
  let myString = '';

  while(myString.length < n - this.length) {
    myString += ch;
  }

  myString += this;

  return myString;
};

String.prototype.padRight = function(ch, n) {
  let myString = this;

  while(myString.length < n) {
    myString += ch;
  }

  return myString;
};

console.log('5'.padLeft('0', 5));
console.log('2'.padRight('.', 2));

String.prototype.padLeft = function(ch, n) {
  if(this.length < n) {
    var diff = n - this.length;
    var tempArr = this.split('');
    var tmp;//from w w w. j  ava 2 s .  co  m
    for(var i = 0; i < diff; i++) {
      tempArr.unshift(ch);
    }
    tmp = tempArr.toString().replace(/,/g, '');
    return tmp;
  }  else if(parseInt(this).toString() !== 'NaN'){
    return parseInt(this);
  } else {
    return this;
  }
};