dojo(二):事件处理

1、在正式进入dojo事件之前，先看一下如何使用dojoConfig配置dojo的行为。

       有两种方式配置，第一种方式使用dojoConfig：    

<!-- set Dojo configuration, load Dojo -->
<script>
    dojoConfig= {
        has: {
            "dojo-firebug": true
        },
        parseOnLoad: false,
        foo: "bar",
        async: true
    };
</script>
<script src="//ajax.googleapis.com/ajax/libs/dojo/1.9.1/dojo/dojo.js"></script>

      第二种方式，使用data-dojo-config属性：

<script src="//ajax.googleapis.com/ajax/libs/dojo/1.9.1/dojo/dojo.js"
        data-dojo-config="has:{'dojo-firebug': true}, parseOnLoad: false, foo: 'bar', async: 1">
</script>

       两种方式是等价的。

2、DOM事件

     Dojo改进了Dom事件处理，通过处理浏览器差异，防止内存泄露等。dojo通过调用dojo/on处理DOM事件。

require(["dojo/on", "dojo/dom", "dojo/dom-style", "dojo/mouse", "dojo/domReady!"],
    function(on, dom, domStyle, mouse) {
        var myButton = dom.byId("myButton"),
            myDiv = dom.byId("myDiv");
 
        on(myButton, "click", function(evt){
            domStyle.set(myDiv, "backgroundColor", "blue");
        });
        on(myDiv, mouse.enter, function(evt){
            domStyle.set(myDiv, "backgroundColor", "red");
        });
        on(myDiv, mouse.leave, function(evt){
            domStyle.set(myDiv, "backgroundColor", "");
        });
});

      Note：默认情况下，dojo/on会以传入的节点（第一个参数）作为上下文环境执行事件处理方法。当需要进行事件委托时，上面的方法需要稍作改动，我们可以使用dojo/_base/lang.hitch来指定事件处理方法执行的上下文环境。  

require(["dojo/on","dojo/dom","dojo/_base/lang","dojo/domReady!"],
    function(on, dom, lang) {
 
        varmyScopedButton1 = dom.byId("myScopedButton1"),
            myScopedButton2 = dom.byId("myScopedButton2"),
            myObject = {
                id:"myObject",
                onClick:function(evt){
                    alert("The scope of this handler is " + this.id);
                }
            };
 
        // This will alert "myScopedButton1"
        on(myScopedButton1,"click", myObject.onClick);
        // This will alert "myObject" rather than "myScopedButton2"
        on(myScopedButton2,"click", lang.hitch(myObject, "onClick"));
 
});

3、NodeList事件

<button id="button1" class="clickMe">Click me</button>
<button id="button2" class="clickMeAlso">Click me also</button>
<button id="button3" class="clickMe">Click me too</button>
<button id="button4" class="clickMeAlso">Please click me</button>
<script>
require(["dojo/query", "dojo/_base/lang", "dojo/domReady!"],
    function(query, lang) {
 
        var myObject = {
            id: "myObject",
            onClick: function(evt){
                alert("The scope of this handler is " + this.id);
            }
        };
        query(".clickMe").on("click", myObject.onClick);
        query(".clickMeAlso").on("click", lang.hitch(myObject, "onClick"));
 
});
</script>

Note：dojo/query返回的结果就是NodeList对象。NodeList是一个JavaScript数组，不过它提供了很多有用的方法来操作数组中的每一个元素。

4、事件发布/订阅

//event.js
define(["dojo/on","dojo/dom","dojo/topic","dojo/domReady"],function(on,dom,topic){
	return {
		publish:function(id){
			var node = dom.byId(id);
			on(node,"click",function(){
				topic.publish("alertuser","i am alerting you");
			});
		}
	};
});

//index.html
<button id="alertButton">Alert the user</button>
     <button id="createAlert">Create another alert button</button>
	 
	 <script src="dojo-release-1.9.1/dojo/dojo.js" data-dojo-config="async:true"></script>
	 <script>
	  require(["custom/event","dojo/topic"],function(event,topic){
		  event.publish("alertButton");
		  topic.subscribe("alertuser",function(text){
			  alert(text);
		  });
	  });
	 </script>

Note：通过dojo/on监听的事件或者通过topic.subscribe订阅的事件都有相应的方法取消。