What is the difference between vue.1 and vue.2

The difference between vue.1 and vue.2: 1. When using the [v-for] instruction in vue2, it can add repeated content; 2. There is a big difference between vue2 and vue1 in that there is no Filter; 3. The communication between the two components is also different.

[Related article recommendations: vue.js]

vue.1 and vue .2 Difference:

Difference 1:

When using the v-for directive in vue2, it can add duplicate content, just like you can add the same Let’s take a look at the content of the message.

The first thing to introduce when writing code is the vue2js file.

html code:

<div id="box">
        <input type="button" value="添加" @click="add()">
        <ul>
            <li v-for="item in arr">{{item}}</li>
        </ul>
    </div>

js code:

 window.onload=function () {
            new Vue({
                el:"#box",
                data:{
                   arr:[1,2,3,4,5,6]
                },
                methods: {
                    add:function () {
                        this.arr.unshift("1")
                    }
                }
            })
        }

However, there is another difference, that is, there is no $index, which is present in vue1. But we can manually add $index

<div id="box">
        <input type="button" value="添加" @click="add()">
        <ul>
            <li v-for="(val,index) in arr">{{val}}------->{{index}}</li>
        </ul>
    </div>

Difference 2:

A big difference between us in vue2 and vue1 is that there is no filter! ! ! When we use filters, we have to define them ourselves.

Difference 3:

Furthermore, we use communication between components differently. Let’s take a look:

HTML code:

<div id="div">
    我是父组件---->{{emitData.msg}}<br>
    <child-com :m="emitData"></child-com>
</div>
</body>
</html>
<template id="tpl">
    <div>
        <span>我是子组件----></span>
        {{m.msg}}<br>
        <input type="button" value="change" @click="change()"/>
    </div>
</template>

js code:

 window.onload = function(){
        new Vue({
            el:"#div",
            data:{
                emitData:{  //写为json 原理：js中对象的引用
                    msg:"我是父组件数据"
                }
            },
            components:{
                'child-com':{
                    props:['m'],
                    template:"#tpl",
                    methods:{
                        change(){
                            this.m.msg='变了';
                        }
                    }
                }
            }
        })
    }

This is not a method in vue2 but we can use this method to solve the problem.

Difference 4:

One of the most basic differences is that when we define a template, we should wrap the template in a big box.

<template id="tpl">
    <div><h3 id="">3333333</h3><strong>strong</strong></div>
</template>

Difference 5:

The life cycle is also different. The life cycle in our vue2 is like this

 window.onload=function () {
            new Vue({
                el:"#box",
                data:{
                    msg:"lalalal"
                },
                beforeCreate () {
                    alert("实例创建之前")
                },
                created() {
                    alert("实例创建完成")
                },
                beforeMount() {
                    alert("数据编译之前")
                },
                mounted() {
                    alert("数据编译完成")
                },
                beforeUpdate:function () {
                    console.log("数据更新之前")
                },
                updated:function () {
                    console.log("数据解析完成")
                },
                beforeDestroy:function () {
                    alert("数据销毁之前")
                },
                destroyed:function () {
                    alert("数据销毁完成")
                }
            })
        }

Finally let’s take a look at the management component communication in a single event

html:

<div id="div">
    <com-a></com-a>
    <com-b></com-b>
    <com-c></com-c>
</div>

js code:

<script>
    window.onload = function(){
        const event=new Vue;
        const A={
            template:`
            <div>
                <span>我是A组件---------></span>{{msg1}}
                <input type="button" value="把a组件的数据传给c" @click="send()">
            </div>
            `,
            data(){
                return{
                    msg1:"我是A组件的数据"
                }
            },
            methods:{
                send(){
                    event.$emit("a-data",this.msg1)
                }
            }
        };
        const B={
            template:`
            <div>
                <span>我是B组件---------></span>{{msg2}}
                <input type="button" value="把b组件的数据传给c" @click="send()">
            </div>
            `,
            data(){
                return{
                    msg2:"我是B组件的数据"
                }
            },
            methods:{
                send(){
                    event.$emit("b-data",this.msg2)
                }
            }
        };
        const C={
            template:`
            <div>
                <h3 id="我是C组件">我是C组件</h3>
                <span>接收到A的数据--->{{a}}</span><br/>
                <span>接收到B的数据--->{{b}}</span>
            </div>
            `,
            data(){
              return{
                  a:"a",
                  b:"b"
              }
            },
            mounted(){
                event.$on("a-data",function (a) {
                    this.a=a;
                }.bind(this));
                event.$on("b-data",function (b) {
                    this.b=b
                }.bind(this))
            }
        };
        new Vue({
            el:"#div",
            data:{
                    msg:"我是父组件数据"
            },
            components:{
               "com-a":A,
               "com-b":B,
               "com-c":C
            }
        })
    }
</script>

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