attachment:simpleAjaxRequest.js of SimpleAJAXRequestToolkit

   1 /*
   2  * simpleAjaxRequest.js
   3  *
   4  * This is a simple AJAX request toolkit. It does not permit pipelining.
   5  * In other words you need to wait for a response before doing a succeeding
   6  * request.
   7  *
   8  * Usage: AJAX.init(url, method, json, callback)
   9  *        url: The URL where the AJAX response will come from.
  10  *             Can be: url = document.location.href + "something/";
  11  *        method: The HTTP method such as GET, POST, PUT, etc.
  12  *        json: When no data is needed this should be 'null' else a JSON
  13  *              object. The object can be retrieved with the 'json' keyword.
  14  *        callback: The callback function that does the work in your code. It
  15  *                  takes two arguments, the request and JSON objects.
  16  *
  17  * Note: 1) If you expect a 100 (continue) or a 204 (no content) response you
  18  *          must define the appropriate callback with the same arguments as
  19  *          above, and set the names as shown below:
  20  *          AJAX.CONTINUE_CB = <continueCB function>
  21  *          AJAX.NO_CONTENT_CB = <noContentCB function>
  22  *
  23  *       2) You should also define a callback with two arguments
  24  *          (request, text), to handle exceptions:
  25  *          AJAX.EXCEPTION_CD = <exceptionCB function>
  26  *
  27  * ----------------------------------
  28  * $Author: $
  29  * $Date: $
  30  * $Revision: $
  31  * ----------------------------------
  32  */
  33 
  34 Function.prototype.bind = function(object) {
  35   var method = this;
  36   return function () {
  37     method.apply(object, arguments);
  38   };
  39 }
  40 
  41 var AJAX = {
  42   _callback: null,
  43   _request: null,
  44   EXCEPTION_CB: null,
  45   CONTINUE_CB: null,
  46   NO_CONTENT_CB: null,
  47 
  48   init: function(url, method, json, callback) {
  49     this._callback = callback;
  50     this._request = AJAX._ajaxRequest();
  51     AJAX._processRequest(url, method, json);
  52   },
  53 
  54   _ajaxRequest: function() {
  55     var request = null;
  56 
  57     try {
  58       request = new XMLHttpRequest();
  59     } catch (e) {
  60       try {
  61         request = new ActiveXObject("Msxml2.XMLHTTP");
  62       } catch (e) {
  63         try {
  64           request = new ActiveXObject("Microsoft.XMLHTTP");
  65         } catch (e) {
  66         }
  67       }
  68     }
  69 
  70     return request;
  71   },
  72 
  73   _processRequest: function(url, method, json) {
  74     if(this._request == null) {
  75       msg = "_processRequest: Invalid XMLHttpRequest object";
  76       this.EXCEPTION_CB(this._request, msg);
  77     }
  78 
  79     method = method.toUpperCase();
  80     var query = null;
  81 
  82     if(json != null) {
  83       query = "";
  84 
  85       if(method == "GET") {
  86         query += url.match(/\?/) ? "&" : "?";
  87       }
  88 
  89       query += "json=" + escape(json);
  90 
  91       if(method == "GET") {
  92         url += query;
  93         query = null;
  94       }
  95     }
  96 
  97     this._request.onreadystatechange = this._handleResponse.bind(this);
  98     this._request.open(method, url, true);
  99 
 100     if(method == "POST") {
 101       this._request.setRequestHeader("Content-type",
 102                                      "application/x-www-form-urlencoded");
 103     }
 104 
 105     this._request.send(query);
 106   },
 107 
 108   _handleResponse: function() {
 109     if(this._request != null && this._request.readyState == 4) {
 110       var status = this._request.status;
 111       var response = null;
 112       var json = this._request.responseText;
 113 
 114       if(status == 200 || status == 201) {
 115         if(/^("(\\.|[^"\\\n\r])*?"|[,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t])+?$/.test(json)) {
 116           json = eval("(" + json + ")");
 117           this._callback(this._request, json);
 118         } else {
 119           msg = "_handleResponse: Invalid JSON Request: " + json;
 120           this.EXCEPTION_CB(this._request, msg);
 121         }
 122       } else if(status == 100) {
 123         if(this.CONTINUE_CB) {
 124           this.CONTINUE_CB();
 125         } else {
 126           msg = "A callback for 100 'Continue' has not been defined.";
 127           this.EXCEPTION_CB(this._request, msg);
 128         }
 129       } else if(status == 204) {
 130         if(this.NO_CONTENT_CB) {
 131           this.NO_CONTENT_CB();
 132         } else {
 133           msg = "A callback for 204 'No Content' has not been defined.";
 134           this.EXCEPTION_CB(this._request, msg);
 135         }
 136       } else {
 137         msg = "Error while retrieving result from the server: " +
 138                (status ? "(" + status : "undefined") + ") " +
 139                this._request.statusText;
 140         this.EXCEPTION_CB(this._request, msg);
 141       }
 142     }
 143   }
 144 }