connection.js

这是YUI的源码及相关示例。里面有很多很炫的Javascript效果。

	},

  /**
   * @description Method for initiating an asynchronous request via the XHR object.
   * @method asyncRequest
   * @public
   * @static
   * @param {string} method HTTP transaction method
   * @param {string} uri Fully qualified path of resource
   * @param {callback} callback User-defined callback function or object
   * @param {string} postData POST body
   * @return {object} Returns the connection object
   */
	asyncRequest:function(method, uri, callback, postData)
	{
		var o = (this._isFileUpload)?this.getConnectionObject(true):this.getConnectionObject();
		var args = (callback && callback.argument)?callback.argument:null;

		if(!o){
			return null;
		}
		else{

			// Intialize any transaction-specific custom events, if provided.
			if(callback && callback.customevents){
				this.initCustomEvents(o, callback);
			}

			if(this._isFormSubmit){
				if(this._isFileUpload){
					this.uploadFile(o, callback, uri, postData);
					return o;
				}

				// If the specified HTTP method is GET, setForm() will return an
				// encoded string that is concatenated to the uri to
				// create a querystring.
				if(method.toUpperCase() == 'GET'){
					if(this._sFormData.length !== 0){
						// If the URI already contains a querystring, append an ampersand
						// and then concatenate _sFormData to the URI.
						uri += ((uri.indexOf('?') == -1)?'?':'&') + this._sFormData;
					}
				}
				else if(method.toUpperCase() == 'POST'){
					// If POST data exist in addition to the HTML form data,
					// it will be concatenated to the form data.
					postData = postData?this._sFormData + "&" + postData:this._sFormData;
				}
			}

			if(method.toUpperCase() == 'GET' && (callback && callback.cache === false)){
				// If callback.cache is defined and set to false, a
				// timestamp value will be added to the querystring.
				uri += ((uri.indexOf('?') == -1)?'?':'&') + "rnd=" + new Date().valueOf().toString();
			}

			o.conn.open(method, uri, true);

			// Each transaction will automatically include a custom header of
			// "X-Requested-With: XMLHttpRequest" to identify the request as
			// having originated from Connection Manager.
			if(this._use_default_xhr_header){
				if(!this._default_headers['X-Requested-With']){
					this.initHeader('X-Requested-With', this._default_xhr_header, true);
				}
			}

			//If the transaction method is POST and the POST header value is set to true
			//or a custom value, initalize the Content-Type header to this value.
			if((method.toUpperCase() === 'POST' && this._use_default_post_header) && this._isFormSubmit === false){
				this.initHeader('Content-Type', this._default_post_header);
			}

			//Initialize all default and custom HTTP headers,
			if(this._has_default_headers || this._has_http_headers){
				this.setHeader(o);
			}

			this.handleReadyState(o, callback);
			o.conn.send(postData || '');


			// Reset the HTML form data and state properties as
			// soon as the data are submitted.
			if(this._isFormSubmit === true){
				this.resetFormState();
			}

			// Fire global custom event -- startEvent
			this.startEvent.fire(o, args);

			if(o.startEvent){
				// Fire transaction custom event -- startEvent
				o.startEvent.fire(o, args);
			}

			return o;
		}
	},

  /**
   * @description This method creates and subscribes custom events,
   * specific to each transaction
   * @method initCustomEvents
   * @private
   * @static
   * @param {object} o The connection object
   * @param {callback} callback The user-defined callback object
   * @return {void}
   */
	initCustomEvents:function(o, callback)
	{
		var prop;
		// Enumerate through callback.customevents members and bind/subscribe
		// events that match in the _customEvents table.
		for(prop in callback.customevents){
			if(this._customEvents[prop][0]){
				// Create the custom event
				o[this._customEvents[prop][0]] = new YAHOO.util.CustomEvent(this._customEvents[prop][1], (callback.scope)?callback.scope:null);

				// Subscribe the custom event
				o[this._customEvents[prop][0]].subscribe(callback.customevents[prop]);
			}
		}
	},

  /**
   * @description This method serves as a timer that polls the XHR object's readyState
   * property during a transaction, instead of binding a callback to the
   * onreadystatechange event.  Upon readyState 4, handleTransactionResponse
   * will process the response, and the timer will be cleared.
   * @method handleReadyState
   * @private
   * @static
   * @param {object} o The connection object
   * @param {callback} callback The user-defined callback object
   * @return {void}
   */

    handleReadyState:function(o, callback)

    {
		var oConn = this;
		var args = (callback && callback.argument)?callback.argument:null;

		if(callback && callback.timeout){
			this._timeOut[o.tId] = window.setTimeout(function(){ oConn.abort(o, callback, true); }, callback.timeout);
		}

		this._poll[o.tId] = window.setInterval(
			function(){
				if(o.conn && o.conn.readyState === 4){

					// Clear the polling interval for the transaction
					// and remove the reference from _poll.
					window.clearInterval(oConn._poll[o.tId]);
					delete oConn._poll[o.tId];

					if(callback && callback.timeout){
						window.clearTimeout(oConn._timeOut[o.tId]);
						delete oConn._timeOut[o.tId];
					}

					// Fire global custom event -- completeEvent
					oConn.completeEvent.fire(o, args);

					if(o.completeEvent){
						// Fire transaction custom event -- completeEvent
						o.completeEvent.fire(o, args);
					}

					oConn.handleTransactionResponse(o, callback);
				}
			}
		,this._polling_interval);
    },

  /**
   * @description This method attempts to interpret the server response and
   * determine whether the transaction was successful, or if an error or
   * exception was encountered.
   * @method handleTransactionResponse
   * @private
   * @static
   * @param {object} o The connection object
   * @param {object} callback The user-defined callback object
   * @param {boolean} isAbort Determines if the transaction was terminated via abort().
   * @return {void}
   */
    handleTransactionResponse:function(o, callback, isAbort)
    {
		var httpStatus, responseObject;
		var args = (callback && callback.argument)?callback.argument:null;

		try
		{
			if(o.conn.status !== undefined && o.conn.status !== 0){
				httpStatus = o.conn.status;
			}
			else{
				httpStatus = 13030;
			}
		}
		catch(e){

			 // 13030 is a custom code to indicate the condition -- in Mozilla/FF --
			 // when the XHR object's status and statusText properties are
			 // unavailable, and a query attempt throws an exception.
			httpStatus = 13030;
		}

		if(httpStatus >= 200 && httpStatus < 300 || httpStatus === 1223){
			responseObject = this.createResponseObject(o, args);
			if(callback && callback.success){
				if(!callback.scope){
					callback.success(responseObject);
				}
				else{
					// If a scope property is defined, the callback will be fired from
					// the context of the object.
					callback.success.apply(callback.scope, [responseObject]);
				}
			}

			// Fire global custom event -- successEvent
			this.successEvent.fire(responseObject);

			if(o.successEvent){
				// Fire transaction custom event -- successEvent
				o.successEvent.fire(responseObject);
			}
		}
		else{
			switch(httpStatus){
				// The following cases are wininet.dll error codes that may be encountered.
				case 12002: // Server timeout
				case 12029: // 12029 to 12031 correspond to dropped connections.
				case 12030:
				case 12031:
				case 12152: // Connection closed by server.
				case 13030: // See above comments for variable status.
					responseObject = this.createExceptionObject(o.tId, args, (isAbort?isAbort:false));
					if(callback && callback.failure){
						if(!callback.scope){
							callback.failure(responseObject);
						}
						else{
							callback.failure.apply(callback.scope, [responseObject]);
						}
					}

					break;
				default:
					responseObject = this.createResponseObject(o, args);
					if(callback && callback.failure){
						if(!callback.scope){
							callback.failure(responseObject);
						}
						else{
							callback.failure.apply(callback.scope, [responseObject]);
						}
					}
			}

			// Fire global custom event -- failureEvent
			this.failureEvent.fire(responseObject);

			if(o.failureEvent){
				// Fire transaction custom event -- failureEvent
				o.failureEvent.fire(responseObject);
			}

		}

		this.releaseObject(o);
		responseObject = null;
    },

  /**
   * @description This method evaluates the server response, creates and returns the results via
   * its properties.  Success and failure cases will differ in the response
   * object's property values.
   * @method createResponseObject
   * @private
   * @static
   * @param {object} o The connection object
   * @param {callbackArg} callbackArg The user-defined argument or arguments to be passed to the callback
   * @return {object}
   */
    createResponseObject:function(o, callbackArg)
    {
		var obj = {};
		var headerObj = {};

		try
		{
			var headerStr = o.conn.getAllResponseHeaders();
			var header = headerStr.split('\n');
			for(var i=0; i<header.length; i++){
				var delimitPos = header[i].indexOf(':');
				if(delimitPos != -1){
					headerObj[header[i].substring(0,delimitPos)] = header[i].substring(delimitPos+2);
				}
			}
		}
		catch(e){}

		obj.tId = o.tId;
		// Normalize IE's response to HTTP 204 when Win error 1223.
		obj.status = (o.conn.status == 1223)?204:o.conn.status;
		// Normalize IE's statusText to "No Content" instead of "Unknown".
		obj.statusText = (o.conn.status == 1223)?"No Content":o.conn.statusText;
		obj.getResponseHeader = headerObj;
		obj.getAllResponseHeaders = headerStr;
		obj.responseText = o.conn.responseText;
		obj.responseXML = o.conn.responseXML;

		if(callbackArg){
			obj.argument = callbackArg;
		}

		return obj;
    },

  /**
   * @description If a transaction cannot be completed due to dropped or closed connections,
   * there may be not be enough information to build a full response object.
   * The failure callback will be fired and this specific condition can be identified
   * by a status property value of 0.
   *
   * If an abort was successful, the status property will report a value of -1.
   *
   * @method createExceptionObject
   * @private
   * @static
   * @param {int} tId The Transaction Id
   * @param {callbackArg} callbackArg The user-defined argument or arguments to be passed to the callback
   * @param {boolean} isAbort Determines if the exception case is caused by a transaction abort
   * @return {object}
   */
    createExceptionObject:function(tId, callbackArg, isAbort)
    {
		var COMM_CODE = 0;
		var COMM_ERROR = 'communication failure';
		var ABORT_CODE = -1;
		var ABORT_ERROR = 'transaction aborted';

		var obj = {};

		obj.tId = tId;
		if(isAbort){
			obj.status = ABORT_CODE;
			obj.statusText = ABORT_ERROR;
		}
		else{
			obj.status = COMM_CODE;
			obj.statusText = COMM_ERROR;
		}

		if(callbackArg){
			obj.argument = callbackArg;
		}

		return obj;
    },

  /**
   * @description Method that initializes the custom HTTP headers for the each transaction.
   * @method initHeader
   * @public
   * @static
   * @param {string} label The HTTP header label
   * @param {string} value The HTTP header value
   * @param {string} isDefault Determines if the specific header is a default header
   * automatically sent with each transaction.
   * @return {void}
   */
	initHeader:function(label, value, isDefault)
	{
		var headerObj = (isDefault)?this._default_headers:this._http_headers;
		headerObj[label] = value;

		if(isDefault){
			this._has_default_headers = true;
		}
		else{
			this._has_http_headers = true;
		}
	},


  /**
   * @description Accessor that sets the HTTP headers for each transaction.
   * @method setHeader
   * @private
   * @static
   * @param {object} o The connection object for the transaction.
   * @return {void}
   */
	setHeader:function(o)
	{
		var prop;
		if(this._has_default_headers){
			for(prop in this._default_headers){
				if(YAHOO.lang.hasOwnProperty(this._default_headers, prop)){
					o.conn.setRequestHeader(prop, this._default_headers[prop]);
				}
			}
		}

		if(this._has_http_headers){
			for(prop in this._http_headers){
				if(YAHOO.lang.hasOwnProperty(this._http_headers, prop)){
					o.conn.setRequestHeader(prop, this._http_headers[prop]);
				}
			}
			delete this._http_headers;

			this._http_headers = {};
			this._has_http_headers = false;
		}
	},

  /**
   * @description Resets the default HTTP headers object
   * @method resetDefaultHeaders
   * @public
   * @static
   * @return {void}
   */
	resetDefaultHeaders:function(){
		delete this._default_headers;
		this._default_headers = {};
		this._has_default_headers = false;
	},

  /**
   * @description This method assembles the form label and value pairs and
   * constructs an encoded string.
   * asyncRequest() will automatically initialize the transaction with a
   * a HTTP header Content-Type of application/x-www-form-urlencoded.
   * @method setForm
   * @public
   * @static
   * @param {string || object} form id or name attribute, or form object.
   * @param {boolean} optional enable file upload.
   * @param {boolean} optional enable file upload over SSL in IE only.
   * @return {string} string of the HTML form field name and value pairs..
   */
	setForm:function(formId, isUpload, secureUri)
	{
        var oForm, oElement, oName, oValue, oDisabled,
            hasSubmit = false,
            data = [], item = 0,
            i,len,j,jlen,opt;

		this.resetFormState();

		if(typeof formId == 'string'){