toLower(str) - Alternative to String.prototype.toLowerCase(), written for a Quora answer.

main.js

function toLower(str){
  var result = '';
  for (var i = 0, len = str.length; i < len; i++) {
    var charAtLocation = str.charCodeAt(i);
    if(charAtLocation > 64 && charAtLocation < 91) //ASCII for upper-case
      result += String.fromCharCode(charAtLocation + 32);
    else
      result += str[i];
  }
  return result;
}