Broadcasting and receiving Vue2.0 events (observer mode)

This article mainly introduces the broadcast and reception of Vue2.0 events (observer mode). Now I share it with you and give it as a reference.

1.Vue1.0 event broadcasting and reception (observer mode)

This method of communicating data between early vue1.0 components , the vue official website provides two methods $dispatch and $broadcast.

But these two methods will be abandoned after vue2.0. The following reasons are given by the vue official website

Official Document

2.Vue2.0 event broadcasting and reception (observer mode)

$emit, $on, $off can be used in vue2.0 Distribute, monitor, and cancel listening events respectively. The simplest official upgrade suggestion is to use a centralized event handler, and it also clearly states that an empty vue instance can do this, because the Vue instance implements an event distribution interface.

Please look at the code directly. During initialization, add an empty vue object named eventhub to the data in the global App.vue file:

new Vue({
 el: '#app',
 router,
 render: h => h(App),
 data: {
  eventHub: new Vue()
 }
})

In this way, we can call the event transmitting and receiving methods in any component. So how does the component transmit and receive? Please look at the front code:

The calling event in a certain component triggers

//通过this.$root.eventHub获取此对象
//调用$emit 方法
this.$root.eventHub.$emit('你的事件名字', 你的需要传送的数据)

and above It means that a component emits an event, which can be understood as I sent a broadcast. If other components need my broadcast, please adjust to my channel. This channel is your event name, and the content of the broadcast is what you sent. Data, then the question is, how do other components receive it? Please see the code

this.$root.eventHub.$on('你的事件名字', (传送的数据)=>{
  handle(yourData)
} )

Components that need to listen to the broadcast can receive it through our globally defined eventHub.$on. The channel is the name of the broadcast event, and the number in the callback is the broadcast content.

3. Write it more concisely

If you have a certain understanding of js, you may know that js has a prototype. This is the main thing Add additional properties to js objects.

For example, declare an object

##

var person=function(){
  this.name="小明";
}

Then we extend this object, such as adding A method of speaking, at this time the useful thing of prototype comes in handy

person.prototype.say=function(){
  alert(this.name);
}

This is expanded The original function object is

when called directly

 var a=new person();

person.say( ); Xiao Ming will pop up. The advantage of this is that no additional memory will be generated, and all instantiated objects will inherit this method from the prototype.

Vue is actually a js class library. Of course, you can also use the magical thing of prototype to expand custom properties. Here are some tips:

Initialize Vue. Add this sentence before app:

Vue.prototype.$eventHub= Vue.prototype.$eventHub || new Vue()

so that we can directly call $eventHub

# inside the component
##The following is a re-transformation of the above method:

Published by

##

//通过this.$root.eventHub获取此对象
//调用$emit 方法
this.$eventHub.$emit('你的事件名字', 你的需要传送的数据)

Receiver

 this.$eventHub.$on('你的事件名字', (传送)=>{
    handle(yourData).
  } )

##4. Close broadcast

To turn off the broadcast, we mainly use $off (your event name) to cancel listening!

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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A brief discussion on js acquisition ModelAndView value problem

Solution to vue page loading flickering problem

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