Javascript: Function to create random string

randomstring.js

var getChars = function (size) {
  var str = '',
  i = 0,
  chars = '0123456789abcdefghijklmnopqurstuvwxyzABCDEFGHIJKLMNOPQURSTUVWXYZ';
  while (i < size) {
    str += chars.substr(Math.floor(Math.random() * 62), 1);
    i++;
  }
  return str;
}
console.log(getChars(8));