query.js

(function (ns) {
  "use strict";

  function UrlQuery() {}

  // Get query string parameter value.
  UrlQuery.get = function (url, field, defaultValue, skipDecode) {
    if (!url) {
      return;
    }

    var re = new RegExp("[?&]" + field + "=([^&]*)");
    var match = url.match(re);
    if (match && match.length > 1) {
      return skipDecode ? match[1] : decodeURIComponent(match[1]);
    } else {
      return defaultValue;
    }
  };

  UrlQuery.getAll = function (url, skipDecode) {
    if (!url) {
      return {};
    }

    var query = {};
    var qsIndex = url.indexOf("?");
    if (url.length > 1 && qsIndex >= 0) {
      var queryParts = url.substring(qsIndex + 1).split("&");
      for (var i = 0; i < queryParts.length; i++) {
        var param = queryParts[i].split("=");
        if (param.length === 2) {
          query[param[0]] = skipDecode ? param[1] : decodeURIComponent(param[1]);
        }
      }
    }

    return query;
  };

  // Add or update query string parameter from an url.
  UrlQuery.update = function (url, field, value, skipEncode) {
    if (url === undefined) {
      return url;
    }

    var re = new RegExp("([?&])" + field + "=[^&]*");
    var match = url.match(re);
    if (match && match.length > 1) {
      return url.replace(re, "$1" + field + "=" + (skipEncode ? value : encodeURIComponent(value)));
    } else {
      var separator = url.indexOf("?") > 0 ? "&": "?";
      return url + separator + field + "=" + (skipEncode ? value : encodeURIComponent(value));
    }
  };

  // Add or update multiple query string parameters from an url.
  UrlQuery.updateAll = function (url, fields, values, skipEncode) {
    if (url === undefined || !fields || !values) {
      return url;
    }

    if (fields.length !== values.length) {
      return url;
    }

    var updatedUrl = url;
    for (var i = 0; i < fields.length; i++) {
      updatedUrl = UrlQuery.update(updatedUrl, fields[i], values[i], skipEncode);
    }

    return updatedUrl;
  };

  // Remove query string parameter from an url.
  UrlQuery.remove = function (url, field) {
    if (url === undefined) {
      return url;
    }

    // Check middle field
    var re = new RegExp("[&]" + field + "=[^&]*");
    if (url.match(re)) {
      return url.replace(re, "");
    }

    // Check last field
    re = new RegExp("[?]" + field + "=[^&]*$");
    if (url.match(re)) {
      return url.replace(re, "");
    }

    // Check first
    re = new RegExp("[?]" + field + "=[^&]*&");
    if (url.match(re)) {
      return url.replace(re, "?");
    }

    return url;
  }

  // Remove multiple query string parameters from an url.
  UrlQuery.removeAll = function (url, fields) {
    if (url === undefined || !fields) {
      return url;
    }

    var updatedUrl = url;
    for (var i = 0; i < fields.length; i++) {
      updatedUrl = UrlQuery.remove(updatedUrl, fields[i]);
    }

    return updatedUrl;
  };

  // In case we have AMD support and also need UrlQuery to be added to the window
  if (typeof ns === "object") {
    ns.UrlQuery = UrlQuery;
  }

  // AMD support - from https://gist.github.com/CrocoDillon/9990078
  if (typeof define === "function" && define.amd) {
    define(function () { return UrlQuery; });
  // CommonJS and Node.js module support.
  } else if (typeof exports !== "undefined") {
    // Support Node.js specific `module.exports` (which can be a function)
    if (typeof module !== "undefined" && module.exports) {
      module.exports = UrlQuery;
    }
    // But always support CommonJS module 1.1.1 spec (`exports` cannot be a function)
    exports.UrlQuery = UrlQuery;
  } else {
    ns.UrlQuery = UrlQuery;
  }
})(this);