Query String Memoization

getQueryParam.js

function getQueryParam(param) {
  if (!this.params) {
    this.params = (function (query) {
      var obj = {};
      if (query) {
        var i = query.length, keyValuePair;
        while (i--) {
          keyValuePair = query[i].split('=');
          if (keyValuePair[0] && keyValuePair[1]) {
            obj[keyValuePair[0]] = keyValuePair[1];
          }
        }
      }
      return obj;
    })(window.location.search.replace(/^\?/, '').split('&'));
  }
  return this.params[param];
}

console.log(getQueryParam("a"));

param.js

var param = function(p) {
  var qs = window.location.search, s = qs.indexOf(p+"=")+1;
  return s ? unescape(qs.substring(s+p.length, (qs.indexOf("&", s)+1 || qs.length+1)-1)) : null;
};