JSFiddle - React, Tailwind, and code Playground

HTML

<div id="result"></div>
<div id="resultpad"></div>
<div id="resultpadsubstr"></div>

JavaScript

var mystring = "t7";

function pad (str, max) {
  str = str.toString();
  return str.length < max ? pad("0" + str, max) : str;
}


String.prototype.hashCode = function() {
  var hash = 0, i, chr, len;
  if (this.length == 0) return hash;
  for (i = 0, len = this.length; i < len; i++) {
    chr   = this.charCodeAt(i);
    hash  = ((hash << 5) - hash) + chr;
    hash |= 0; // Convert to 32bit integer
  }
  return hash;
};

var max_length =7;
$('#result').text(mystring.hashCode());
$('#resultpad').text(pad(mystring.hashCode(), max_length));		//just padded
$('#resultpadsubstr').text(pad(mystring.hashCode().toString().substr(0,max_length), max_length)); //padded and cut above 7