Vue's event bubble most detailed explanation version

Ichiro Qiu Shan 2020-11-13 02:57:32
vue event bubble detailed explanation


Let's start with bubbling , We all know that when there are bubbles in the water , Bubbles will rise from the bottom of the water , From deep to shallow . But water goes through different depths of water as it rises .
So let's explain what event bubbling is , If you know the properties of the browser , A page is a stream of documents ( namely dom Made up of trees ), When we're in
A time trigger , This event is like this bubble , from dom The bottom of the tree , Layer by layer pass up , All the way to dom The root node , If the child element and the parent element trigger the same event , When the child element is triggered, the parent element is also triggered by the bubbling mechanism , This is the basic principle of bubbling .
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In different kernel browsers , Bubbling is different

IE<11: div => body => html => document

In other kernels :div => body =>html => window

Be careful : stay JavaScript in , Not all events can bubble , image :blur、unload、load You can't bubble when you wait for events

Sample code :
Html

<div id="app">
<div id="father">
<div id="child">
I'm a child element
</div>
I'm a parent element
</div>
</div>

CSS

#app{

width: 500px;
height: 500px;
margin: 200px auto;
background-color: #f5f5f5;
border:2px solid #dddddd;
}
#father{

width: 400px;
height: 400px;
background-color: rgb(168, 125, 125);
text-align: center;
color:red;
}
#child{

width: 200px;
height: 200px;
background-color: #fff;
color:blue;
}

js

var father = document.getElementById('father');
var child = document.getElementById('child');
father.addEventListener("click", function () {

console.log(' I'm a parent element ')
}, false)
child.addEventListener("click", function () {

console.log(' I'm a subset element ')
}, false)

 Insert picture description here
When I click on a child element , The console is printed as shown below :
 Insert picture description here
When I click on the parent element : The console is printed as follows :
 Insert picture description here
You can see , When I click on the sub element , The click event of the parent element binding is also triggered .
So how can we stop this kind of event from passing on ?

How to prevent events from bubbling

Don't talk nonsense , Go straight to the code
JS

var father = document.getElementById('father');
var child = document.getElementById('child');
father.addEventListener("click", function () {

if(event && event.stopPropagation){

event.stopPropagation() // Not IE browser 
}else{

event.cancelBubble = true; //IE browser 
}
console.log(' I'm a parent element ')
}, false)
child.addEventListener("click", function () {

if (event && event.stopPropagation) {

event.stopPropagation() // Not IE browser 
} else {

event.cancelBubble = true; //IE browser 
}
console.log(' I'm a subset element ')
}, false)

stay W3C in , Regulations DOM Standard through call event Object's stopPropagation() Method to prevent further propagation of bubbling events .

So in vue How do we use ?

We can use .stop Modifiers are bound to child elements , Prevent it from bubbling to the parent element , So as not to trigger bubble event

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<style>
#app{

width: 500px;
height: 500px;
margin: 200px auto;
background-color: #f5f5f5;
border:2px solid #dddddd;
}
.father{

width: 400px;
height: 400px;
background-color: rgb(168, 125, 125);
text-align: center;
color:red;
}
.child{

width: 200px;
height: 200px;
background-color: #fff;
color:blue;
}
</style>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<body>
<div id="app">
<div class="father" @click="clickFather">
<div class="child" @click.stop="clickChild">
I'm a child element
</div>
I'm a parent element
</div>
</div>
<script>
var app = new Vue({

el:"#app",
data:{

},
methods:{

clickFather(){

console.log(' I'm a parent element ')
},
clickChild(){

console.log(' I'm a child element ')
}
}
})
</script>
</body>
</html>

Click the sub element to print out the log
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Of course , Event bubbling is the default behavior of browsers , The reason for this design , There is a reason , Because sometimes the event bubble can provide a lot of convenience , But improper use will cause a lot of unnecessary bug.

summary :1. The basic principle of event bubbling
2. Native js and vue How to prevent the event from bubbling

版权声明
本文为[Ichiro Qiu Shan]所创,转载请带上原文链接,感谢

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