《JavaScript 源码分析》之 jquery.unobtrusive-ajax.js

 /*!
 ** Unobtrusive Ajax support library for jQuery
 ** Copyright (C) Microsoft Corporation. All rights reserved.
 */

 /*jslint white: true, browser: true, onevar: true, undef: true, nomen: true, eqeqeq: true, plusplus: true, bitwise: true, regexp: true, newcap: true, immed: true, strict: false */
 /*global window: false, jQuery: false */
 /*
 data-ajax=true //开启绑定

 data-ajax-mode//更新的形式 BEFORE插入到对象之前 AFTER插入到对象之后 为空就是覆盖
 data-ajax-update//更新的对象
 data-ajax-confirm//设置一个确定取消弹出框的文字，没有则不设置
 data-ajax-loading//显示loading的对象
 data-ajax-loading-duration//持续时间 默认是0
 data-ajax-method//提交方式
 data-ajax-url//提交url
 data-ajax-begin//ajax前触发的函数或者一段程序
 data-ajax-complete//完成后，此时还没有加载返回的数据，请求成功或失败时均调用
 data-ajax-success//成功，加载完成的数据
 data-ajax-failure//失败

 */

 (function ($) {
     var data_click = "unobtrusiveAjaxClick",
         data_validation = "unobtrusiveValidation";
     //第二核心，判断是否函数，不是则构造一个匿名函数
     function getFunction(code, argNames) {
         var fn = window, parts = (code || "").split(".");
         while (fn && parts.length) {
             fn = fn[parts.shift()];
         }//查找函数名有时候是命名空间比如xxx.xxx
         if (typeof (fn) === "function") {
             return fn;
         }
         argNames.push(code);
         //如果不是函数对象则自己构造一个并返回，吊！
         return Function.constructor.apply(null, argNames);
     }

     function isMethodProxySafe(method) {
         return method === "GET" || method === "POST";
     }
     //可以添加各种提交方式，应该是为Web Api做的补充
     function asyncOnBeforeSend(xhr, method) {
         if (!isMethodProxySafe(method)) {
             xhr.setRequestHeader("X-HTTP-Method-Override", method);
         }
         //注：X-HTTP-Method-Override是一个非标准的HTTP报头。
         //这是为不能发送某些HTTP请求类型（如PUT或DELETE）的客户端而设计的
     }
     //完成后的
     function asyncOnSuccess(element, data, contentType) {
         var mode;

         if (contentType.indexOf("application/x-javascript") !== -1) {  // jQuery already executes JavaScript for us
             return;
         }

         mode = (element.getAttribute("data-ajax-mode") || "").toUpperCase();
         $(element.getAttribute("data-ajax-update")).each(function (i, update) {
             var top;

             switch (mode) {
             case "BEFORE":
                 top = update.firstChild;
                 $("<div />").html(data).contents().each(function () {
                     update.insertBefore(this, top);
                 });
                 break;
             case "AFTER":
                 $("<div />").html(data).contents().each(function () {
                     update.appendChild(this);
                 });
                 break;
             default:
                 $(update).html(data);
                 break;
             }
         });
     }
     //主要函数
     //绑定的对象和参数
     function asyncRequest(element, options) {
         var confirm, loading, method, duration;

         confirm = element.getAttribute("data-ajax-confirm");
         if (confirm && !window.confirm(confirm)) {
             return;
         }

         loading = $(element.getAttribute("data-ajax-loading"));//
         duration = element.getAttribute("data-ajax-loading-duration") || 0;//默认是0

         $.extend(options, {
             type: element.getAttribute("data-ajax-method") || undefined,
             url: element.getAttribute("data-ajax-url") || undefined,
             beforeSend: function (xhr) {//ajax前触发，此处的xhr将在下面用apply传递出去
                 var result;
                 asyncOnBeforeSend(xhr, method);//判断是否添加特种的提交方式
                 result = getFunction(element.getAttribute("data-ajax-begin"), ["xhr"]).apply(this, arguments);//argument：替换函数对象的其中一个属性对象，存储参数。这里是将原先的参数传递出去，吊！
                 if (result !== false) {
                     loading.show(duration);
                 }
                 return result;
             },
             complete: function () {
                 loading.hide(duration);
                 getFunction(element.getAttribute("data-ajax-complete"), ["xhr", "status"]).apply(this, arguments);
             },
             success: function (data, status, xhr) {
                 asyncOnSuccess(element, data, xhr.getResponseHeader("Content-Type") || "text/html");
                 getFunction(element.getAttribute("data-ajax-success"), ["data", "status", "xhr"]).apply(this, arguments);
             },
             error: getFunction(element.getAttribute("data-ajax-failure"), ["xhr", "status", "error"])
         });

         options.data.push({ name: "X-Requested-With", value: "XMLHttpRequest" });

         method = options.type.toUpperCase();//大写
         if (!isMethodProxySafe(method)) {
             options.type = "POST";
             options.data.push({ name: "X-HTTP-Method-Override", value: method });
         }
         //最后都是调用jquery的ajax
         $.ajax(options);
     }

     function validate(form) {
         //可以取消验证
         var validationInfo = $(form).data(data_validation);
         return !validationInfo || !validationInfo.validate || validationInfo.validate();
     }

     $(document).on("click", "a[data-ajax=true]", function (evt) {
         evt.preventDefault();
         asyncRequest(this, {
             url: this.href,
             type: "GET",
             data: []
         });
     });

     $(document).on("click", "form[data-ajax=true] input[type=image]", function (evt) {//这个不常用
         var name = evt.target.name,
             $target = $(evt.target),
             form = $target.parents("form")[0],
             offset = $target.offset();

         $(form).data(data_click, [
             { name: name + ".x", value: Math.round(evt.pageX - offset.left) },
             { name: name + ".y", value: Math.round(evt.pageY - offset.top) }
         ]);

         setTimeout(function () {
             $(form).removeData(data_click);
         }, 0);
     });

     $(document).on("click", "form[data-ajax=true] :submit", function (evt) {
         var name = evt.target.name,
             form = $(evt.target).parents("form")[0];

         $(form).data(data_click, name ? [{ name: name, value: evt.target.value }] : []);

         setTimeout(function () {
             $(form).removeData(data_click);
         }, 0);
     });

     $(document).on("submit", "form[data-ajax=true]", function (evt) {
         var clickInfo = $(this).data(data_click) || [];
         evt.preventDefault();
         if (!validate(this)) {
             return;
         }
         asyncRequest(this, {
             url: this.action,
             type: this.method || "GET",
             data: clickInfo.concat($(this).serializeArray())//写得好，序列化表单并拼接，以后的ajax都可以这样，方便啊
         });
     });
 }(jQuery));