Mounted application does not replace the element 破壊的変更
Overview
In Vue 2.x, when mounting an application that has a template, the rendered content replaces the element we mount to. In Vue 3.x, the rendered application is appended as a child of such an element, replacing element's innerHTML.
2.x Syntax
In Vue 2.x, we pass an HTML element selector to new Vue() or $mount:
new Vue({
el: '#app',
data() {
return {
message: 'Hello Vue!'
}
},
template: `
<div id="rendered">{{ message }}</div>
`
})
// or
const app = new Vue({
data() {
return {
message: 'Hello Vue!'
}
},
template: `
<div id="rendered">{{ message }}</div>
`
})
app.$mount('#app')
When we mount this application to the page that has a div with the passed selector (in our case, it's id="app"):
<body>
<div id="app">
Some app content
</div>
</body>
in the rendered result, the mentioned div will be replaced with the rendered application content:
<body>
<div id="rendered">Hello Vue!</div>
</body>
3.x Syntax
In Vue 3.x, when we mount an application, its rendered content will replace the innerHTML of the element we pass to mount:
const app = Vue.createApp({
data() {
return {
message: 'Hello Vue!'
}
},
template: `
<div id="rendered">{{ message }}</div>
`
})
app.mount('#app')
When this app is mounted to the page that has a div with id="app", this will result in:
<body>
<div id="app" data-v-app="">
<div id="rendered">Hello Vue!</div>
</div>
</body>
Migration Strategy
Migration build flag: GLOBAL_MOUNT_CONTAINER