使用方法 --- 4个before，4个ed，创造，装载，更新，销毁
初始化阶段
beforeCreate(){} // 准备怀孕
created(){} // 怀上了 *******************************************
beforeMount(){} // 准备生
mounted(){} // 生下来了 *************************************************
运行时阶段
beforeUpdate(){} // 每天都在长大
updated(){} ************************
销毁阶段
beforeDestroy(){} // 马上 game over
destroyed(){} // game over gg ************
综上所述，会在 created 或者 mounted 中请求数据
如果必须使用dom操作，那么可以在 mounted 和 updated 中
<!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>
<body>
<div id="app">
<button @click="des">销毁</button>
<button @click="add">修改状态</button>{{ count }}
</div>
</body>
<script src="vue.js"></script>
<script>
new Vue({
el: '#app',
data: {
count: 0
},
methods: {
add () {
this.count += 1
},
des () {
this.$destroy() // 触发销毁
}
},
beforeCreate () {
console.log('创建实例之前', this.$el) // undefined
console.log('创建实例之前', this.$data) // undefined
console.log('创建实例之前', this.count) // undefined
},
created () {
console.log('创建实例成功', this.$el) // undefined
console.log('创建实例成功', this.$data) // {count: 0}
console.log('创建实例成功', this.count) // 0
},
beforeMount () {
console.log('装载之前', this.$el) // <div id="app"></div>
console.log('装载之前', this.$data) // {count: 0}
console.log('装载之前', this.count) // 0
},
mounted () {
console.log('装载之后', this.$el) // <div id="app"></div>
console.log('装载之后', this.$data) // {count: 0}
console.log('装载之后', this.count) // 0
},
beforeUpdate () {
console.log('更新之前', this.$el) // <div id="app"></div>
console.log('更新之前', this.$data) // {count: 0}
console.log('更新之前', this.count) // 1
},
updated () {
console.log('更新之后', this.$el) // <div id="app"></div>
console.log('更新之后', this.$data) // {count: 0}
console.log('更新之后', this.count) // 1
},
beforeDestroy () {
console.log('销毁之前', this.$el) // <div id="app"></div>
console.log('销毁之前', this.$data) // {count: 0}
console.log('销毁之前', this.count) // 1
},
destroyed () {
console.log('销毁之后', this.$el) // <div id="app"></div>
console.log('销毁之后', this.$data) // {count: 0}
console.log('销毁之后', this.count) // 1
}
})
</script>
</html>
AJAX请求数据
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
ul li{
list-style: none;
}
</style>
</head>
<body>
<div id="app">
<ul>
<li v-for="item of list" :key="item.userid">
{{item.username}}--{{item.age}}--{{item.sex}}
</li>
</ul>
</div>
</body>
<script src="../jquery.min.js"></script>
<script src="../vue.js"></script>
<script>
new Vue({
el:"#app",
data:{
list:[]
},
created(){
$.ajax({
url:"http://localhost:3000/users",
success:(data)=>{
console.log(data.data)
this.list=data.data
}
})
}
})
</script>
</html>
fetch请求数据
<!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>
<body>
<div id="app">
<ul>
<li v-for="item of list" :key="item.userid">{{ item.username }}</li>
</ul>
</div>
</body>
<script src="vue.js"></script>
<script>
new Vue({
el: '#app',
data: {
list: []
},
created () {
fetch('http://localhost:3000/users').then(res => res.json()).then(data => {
console.log(data)
this.list = data.data
})
}
})
</script>
</html>
axios请求数据
<!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>
<body>
<div id="app">
<ul>
<li v-for="item of list" :key="item.userid">{{ item.username }}</li>
</ul>
</div>
</body>
<script src="vue.js"></script>
<script src="axios.js"></script>
<script>
new Vue({
el: '#app',
data: {
list: []
},
created () {
// $.get
axios.get('http://localhost:3000/users').then(res => {
console.log(res.data.data)
this.list = res.data.data
})
}
})
</script>
</html>
如果使用post请求：
fetch(url).then(
// 得到的是 promise 对象，前端需要的json数据，需要将其转换为json数据
// res => res.json()
function (res) { return res.json() }
).then(
// 得到的就是json对象，可以供前端直接使用
data => console.log(data)
)
``` **默认的是get的请求方式,如果为post请求呢** ```
fetch('http://****/login', {
method: 'POST',
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
},
body: JSON.stringify({username: '', password: ''})
}).then(function(response) {
console.log(response);
});
axios.get(url).then(res => {})
axios.post(url, {username: ''}).then(res => {})
axios({
url: '',
method: 'post',
data: {
username: ''
}
}).then(res => {})
