【dojo】 on/emit subscribe/publish

最近dojo evneted的两个概念一直没搞清楚，跟同事打赌，我自己肯定能查得到，结果，看了其他人的代码加上官网翻了一遍，算是有点理解了。

on/emit 

 

emit，某个对象发出事件。

 

Argument	Type	Description
target	Object	This is the target object (a DOM node or other event emitting object) that will be the source of the event. The target object may be a host object with its own event capabilities (like DOM elements or the window), or it may be a JavaScript object with an on() method.
type	String	This is the name of the event type to be dispatched (like select). This event may be a standard event (like click) or a custom event (like finished).
event	Object	This is an object with the properties of the event to be dispatched. Generally you should align your properties with W3C standards. Two properties are of particular importance: bubbles - This indicates that the event should bubble up, first firing on the target object, next on the target object's parent (parentNode) and so on until it reaches the top of the DOM or bubbling is stopped. Bubbling is stopped when a listener callsevent.stopPropagation(). cancelable - This indicates that the event's default action can be cancelled. The default action is cancelled by a listener by calling event.preventDefault(). The emit method does not perform any default action, it returns a value allowing the calling code to perform any default action.

 

on是订阅指定某个对象的消息。

 

Name	Type	Description
target	Element|Object	This is the target object or DOM element that to receive events from
type	String|Function	This is the name of the event to listen for or an extension event type.
listener	Function	This is the function that should be called when the event fires.
dontFix	undefined

 

比如自定义一个widget，创建按钮点击事件为_onStopRender

 

 

<button data-dojo-type="dijit/form/Button" type="submit" data-dojo-attach-point = "createJob"data-dojo-attach-event="onClick:              　　　　　_onStopRender" >创建</button>

 

---------------------------------------------------------  

 

widget部分发布一个createJob的事件：

                 

 _onStopRender : function(){
                              this.emit("createJob",{});

 }

                             

 

----------------------------------------------

UI部分new了widget之后，去订阅它的事件：

 

                               var iDialog= new JobDialog().placeAt("createJobProperties");

 

                              on(iDialog,"createJob",function(){    
                                   alert(0);
                              });     

 

subscribe/publish 

 

publish 发出一个事件。

subscribe用于匿名事件，不晓得到底是哪个对象发出的。(胆儿够肥的，匿名也接。。。)

官网例子：

<button id="alertButton">Alert the user</button>

<button id="createAlert">Create another alert button</button>

---------------------------------------------------------------------------- 

<script>

require(["dojo/on", "dojo/topic", "dojo/dom-construct", "dojo/dom", "dojo/domReady!"],

    function(on, topic, domConstruct, dom) {

        var alertButton = dom.byId("alertButton"),

            createAlert = dom.byId("createAlert");

        

　　　　on(alertButton, "click", function() {

            // When this button is clicked,

            // publish to the "alertUser" topic

            topic.publish("alertUser", "I am alerting you.");

        });

 

        on(createAlert, "click", function(evt){

            // Create another button

            var anotherButton = domConstruct.create("button", {

                innerHTML: "Another alert button"

            }, createAlert, "after");

             // When the other button is clicked,

            // publish to the "alertUser" topic

            on(anotherButton, "click", function(evt){

                topic.publish("alertUser", "I am also alerting you.");

            });

        });

 

        // Register the alerting routine with the "alertUser" topic.

        topic.subscribe("alertUser", function(text){

            alert(text);

        });

});

</script>

  

 

 参考：

http://livedocs.dojotoolkit.org/dojo/on

http://dojotoolkit.org/documentation/tutorials/1.7/events/