Vue 之五 生命周期钩子函数 自定义指令 过滤器

一、生命周期钩子函数

Vue组件的生命周期一共有8个函数目前只需要掌握2个

    1 mounted用的最多：向后端发送请求，定时器初始化
    2 destroyed：组件销毁--->给组件写一个定时器-->组件销毁，定时器清除

 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <script src="js/vue.js"></script>
    <title>Title</title>
</head>
<body>

<div id="box">
    <child v-if="isShow"></child>

    {{name}}

</div>


</body>
<script>

    Vue.component('child', {
        template: `
        <div>我是组件的div</div>`,
        data(){
            return {
                t:null,
            }
        },
        beforeCreate() {
            console.log('beforeCreate')
        },
        created() {
            console.log('created')
        },
        beforeMount() {
            console.log('beforeMount')
        },
        mounted() {
            //用的最多，向后端加载数据，创建定时器等
            console.log("页面已被vue实例渲染, data, methods已更新");
            console.log('mounted')
            //起一个定时器，每隔三秒，打印一行
            this.t = setInterval(function () {
                console.log('daada')
            }, 3000)
        },
        beforeUpdate() {
            console.log('beforeUpdate')
        },
        updated() {
            console.log('updated')
        },
        beforeDestroy() {
            console.log('beforeDestroy')
        },
        destroyed() {
            //组件销毁，清理定时器
            clearInterval(this.t)
            this.t = null
            console.log('destroyed')
        },
    })


    var vm = new Vue({
        el: '#box',
        data: {
            name:'lqz',
            isShow:true
        },
        beforeUpdate() {
            console.log('根的---beforeUpdate')
        },
        updated() {
            console.log('根的---updated')
        },

    })



</script>
</html>

2 补充延时任务和定时任务

 setTimeout(function () {
        alert(33333)
    },3000) //延迟3s钟干什么事


    setInterval(
        function () {
            alert(444)

        },3000
    )//每隔3s钟干什么事

二、自定义指令
1 基本使用

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>自定义指令 基本使用</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.12/vue.min.js"></script>
</head>
<body>

<div id="box">
    <div v-mystyle>我是1个DIV</div>
</div>

</body>
<script>
    // 自定义指令，使用的时候 v-自定义指令名
    Vue.directive('mystyle', {
        inserted(ev) {    // 在标签上使用这个指令，就会触发 inserted
            console.log('我执行了')
        }
    })


    let vm = new Vue({
        el: '#box'
    })
</script>
</html>

 

2.让所有使用自定义指令的标签背景都变红色

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>自定义指令 基本使用</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.12/vue.min.js"></script>
</head>
<body>

<div id="box">
    <div v-mystyle>我是1个DIV</div>
    <br>
    <div v-mystyle>我也是1个DIV</div>
</div>

</body>
<script>
    // 自定义指令，使用的时候 v-自定义指令名
    Vue.directive('mystyle', {
        inserted(ev) {    // 在标签上使用这个指令，就会触发 inserted
            ev.style.background='red'
        }
    })

    let vm = new Vue({
        el: '#box'
    })
</script>
</html>

 

3.用户指定自定义指令的背景色,修改变量，背景变化

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>自定义指令</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.12/vue.min.js"></script>
</head>
<body>

<div id="box">
    <!--    <div v-mystyle>我是1个DIV</div>-->
    <div v-mystyle>我是1个DIV</div>
    <div v-mystyle="'red'">我是1个DIV</div>
    <div v-mystyle="'green'">我是1个DIV</div>
    <div v-mystyle="'blue'">我是1个DIV</div>
    <div v-mystyle="myColor">我是1个DIV</div>
</div>

</body>
<script>
    Vue.directive('mystyle', {
        inserted(ev, color) {    // 这里的ev就是DOM对象，color是自定义组件对象
            console.log(ev)
            console.log(color)
            ev.style.backgrond = color.value
        },
        updated(el, color) {
            el.style.background = color.value
        }
    })

    let vm = new Vue({
        el: '#box',
        data: {
            myColor: 'purple'
        }
    })
</script>
</html>

三：过滤器

 

json数据：film.json

{
  "coming": [
    {
      "id": 1240838,
      "haspromotionTag": false,
      "img": "http://p1.meituan.net/w.h/movie/38dd31a0e1b18e1b00aeb2170c5a65b13885486.jpg",
      "version": "",
      "nm": "除暴",
      "preShow": false,
      "sc": 8.6,
      "globalReleased": true,
      "wish": 76513,
      "star": "王千源,吴彦祖,春夏",
      "rt": "2020-11-20",
      "showInfo": "今天50家影院放映79场",
      "showst": 3,
      "wishst": 0,
      "comingTitle": "11月20日 周五"
    },
    {
      "id": 1228788,
      "haspromotionTag": false,
      "img": "http://p0.meituan.net/w.h/movie/b16c1c0d5ac9e743c6ffbbf7eba900522725807.jpg",
      "version": "",
      "nm": "一秒钟",
      "preShow": false,
      "sc": 8.6,
      "globalReleased": true,
      "wish": 54493,
      "star": "张译,刘浩存,范伟",
      "rt": "2020-11-27",
      "showInfo": "今天11家影院放映12场",
      "showst": 3,
      "wishst": 0,
      "comingTitle": "11月27日 周五"
    },
    {
      "id": 1358968,
      "haspromotionTag": false,
      "img": "http://p0.meituan.net/w.h/movie/d33858dbfc207da3b36c0dc7fff7a8bb2028677.jpg",
      "version": "",
      "nm": "汪汪队立大功之超能救援",
      "preShow": false,
      "sc": 8.3,
      "globalReleased": true,
      "wish": 24833,
      "star": "杨鸥,韩娇娇,李敏妍",
      "rt": "2020-11-13",
      "showInfo": "今天5家影院放映7场",
      "showst": 3,
      "wishst": 0,
      "comingTitle": "11月13日 周五"
    },
    {
      "id": 345809,
      "haspromotionTag": false,
      "img": "http://p1.meituan.net/w.h/moviemachine/7c4ba9633635503044a8f8fb6426aa8d416264.jpg",
      "version": "v2d imax",
      "nm": "隐形人",
      "preShow": false,
      "sc": 8.4,
      "globalReleased": true,
      "wish": 9894,
      "star": "伊丽莎白·莫斯,奥利弗·杰森-科恩,阿尔迪斯·霍吉",
      "rt": "2020-12-04",
      "showInfo": "今天21家影院放映30场",
      "showst": 3,
      "wishst": 0,
      "comingTitle": "12月4日 周五"
    },
    {
      "id": 1330790,
      "haspromotionTag": false,
      "img": "http://p0.meituan.net/w.h/movie/88e54f3e670789ba1f08e48a5f1170c1188102.jpg",
      "version": "",
      "nm": "明天你是否依然爱我",
      "preShow": false,
      "sc": 0,
      "globalReleased": false,
      "wish": 217699,
      "star": "杨颖,李鸿其,黄柏钧",
      "rt": "2020-12-24",
      "showInfo": "2020-12-24 下周四上映",
      "showst": 4,
      "wishst": 0,
      "comingTitle": "12月24日 周四"
    },
    {
      "id": 1277751,
      "haspromotionTag": false,
      "img": "http://p0.meituan.net/w.h/movie/303c2e671cc4df875c151d688ecbd8962085989.jpg",
      "version": "v2d imax",
      "nm": "赤狐书生",
      "preShow": false,
      "sc": 7.7,
      "globalReleased": true,
      "wish": 177525,
      "star": "陈立农,李现,哈妮克孜",
      "rt": "2020-12-04",
      "showInfo": "今天26家影院放映43场",
      "showst": 3,
      "wishst": 0,
      "comingTitle": "12月4日 周五"
    },
    {
      "id": 1225578,
      "haspromotionTag": false,
      "img": "http://p0.meituan.net/w.h/moviemachine/cf7d6942f2aa9189cce20519b490b6b1879487.jpg",
      "version": "",
      "nm": "野性的呼唤",
      "preShow": false,
      "sc": 9.2,
      "globalReleased": true,
      "wish": 14703,
      "star": "哈里森·福特,丹·史蒂文斯,凯伦·吉兰",
      "rt": "2020-11-13",
      "showInfo": "今天暂无场次",
      "showst": 3,
      "wishst": 0,
      "comingTitle": "11月13日 周五"
    },
    {
      "id": 1302281,
      "haspromotionTag": false,
      "img": "http://p0.meituan.net/w.h/moviemachine/1d2b4985d0187b437d41a73994ba2e191607376.jpg",
      "version": "",
      "nm": "奇妙王国之魔法奇缘",
      "preShow": true,
      "sc": 0,
      "globalReleased": false,
      "wish": 20309,
      "star": "卢瑶,张洋,陈新玥",
      "rt": "2020-12-26",
      "showInfo": "2020-12-26 下周六上映",
      "showst": 4,
      "wishst": 0,
      "comingTitle": "12月26日 周六"
    },
    {
      "id": 1301902,
      "haspromotionTag": false,
      "img": "http://p0.meituan.net/w.h/movie/f686425a1ad1f502254abef593d508bf428685.jpg",
      "version": "",
      "nm": "沉默东京",
      "preShow": false,
      "sc": 5.8,
      "globalReleased": true,
      "wish": 52,
      "star": "佐藤浩市,石田百合子,西岛秀俊",
      "rt": "2020-12-04",
      "showInfo": "今天暂无场次",
      "showst": 3,
      "wishst": 0,
      "comingTitle": ""
    },
    {
      "id": 1286015,
      "haspromotionTag": false,
      "img": "http://p0.meituan.net/w.h/moviemachine/a0c6d6e130abe399e4cba58be2b1f871840268.jpg",
      "version": "",
      "nm": "宝可梦：超梦的逆袭 进化",
      "preShow": false,
      "sc": 8.2,
      "globalReleased": true,
      "wish": 53255,
      "star": "松本梨香,大谷育江,市村正亲",
      "rt": "2020-12-04",
      "showInfo": "今天10家影院放映10场",
      "showst": 3,
      "wishst": 0,
      "comingTitle": "12月4日 周五"
    }
  ]
}

前端：index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>过滤器</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.12/vue.min.js"></script>
    <script src="https://cdn.bootcdn.net/ajax/libs/axios/0.21.0/axios.min.js"></script>
</head>
<body>

<div id="box">
    <ul>
        <li v-for="item in dataList">
            <h2>{{item.nm}}</h2>
            <p>主演：{{item.star}}</p>
            <img :src="item.img | repUrl" alt="">
        </li>
    </ul>
</div>

</body>
<script>
    // 过滤器
    Vue.filter('repUrl', function (url) {
        return url.replace('w.h','128.180')
    })
    let vm = new Vue({
        el: '#box',
        data: {
            dataList: ''
        },
        mounted() {
            axios.get("http://127.0.0.1:5000/").then(res => {
                console.log(res.data.coming)
                this.dataList = res.data.coming
            }).catch(err => {
                console.log(err);
            })
        }
    })
</script>
</html>

后端：main.py

import json

from flask import Flask, jsonify

app = Flask(__name__)


@app.route('/')
def index():
    print('请求来了')
    with open('film.json', mode='rt', encoding='utf-8') as f:
        dic = json.load(f)
    res = jsonify(dic)
    res.headers['Access-Control-Allow-Origin'] = '*'
    return res


if __name__ == '__main__':
    app.run()
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原文地址：https://www.cnblogs.com/ltyc/p/14157124.html