Angular query string utilities

qs.js

// expose angular query string utilities
(function () {
  'use strict';

  var module = angular.module('myQueryString', []);
  module.factory('myQueryString.QueryString', [function () {

    var forEach = angular.forEach;
    var hasOwnProperty = angular.hasOwnProperty;
    var isArray = angular.isArray;
    var isDefined = angular.isDefined;

    // a private function in angular.js
    function encodeUriQuery(val, pctEncodeSpaces) {
      return encodeURIComponent(val).
          replace(/%40/gi, '@').
          replace(/%3A/gi, ':').
          replace(/%24/g, '$').
          replace(/%2C/gi, ',').
          replace(/%20/g, (pctEncodeSpaces ? '%20' : '+'));
    }

    // a private function in angular.js
    function tryDecodeURIComponent(value) {
      try {
        return decodeURIComponent(value);
      } catch (e) {
        // Ignore any invalid uri component
      }
    }

    // a private function in angular.js
    function parseKeyValue(/**string*/keyValue) {
      var obj = {}, key_value, key;
      forEach((keyValue || "").split('&'), function (keyValue) {
        if (keyValue) {
          key_value = keyValue.split('=');
          key = tryDecodeURIComponent(key_value[0]);
          if (isDefined(key)) {
            var val = isDefined(key_value[1]) ? tryDecodeURIComponent(key_value[1]) : true;
            if (!hasOwnProperty.call(obj, key)) {
              obj[key] = val;
            } else if (isArray(obj[key])) {
              obj[key].push(val);
            } else {
              obj[key] = [obj[key], val];
            }
          }
        }
      });
      return obj;
    }

    // a private function in angular.js
    function toKeyValue(obj) {
      var parts = [];
      forEach(obj, function (value, key) {
        if (isArray(value)) {
          forEach(value, function (arrayValue) {
            parts.push(encodeUriQuery(key, true) +
                (arrayValue === true ? '' : '=' + encodeUriQuery(arrayValue, true)));
          });
        } else {
          parts.push(encodeUriQuery(key, true) +
              (value === true ? '' : '=' + encodeUriQuery(value, true)));
        }
      });
      return parts.length ? parts.join('&') : '';
    }

    return {
      parseKeyValue:  parseKeyValue,
      toKeyValue:     toKeyValue
    }
  }]);
})();