Vue basic finishing 1

Diagram of the relationship between MVC and MVVM

1. mvc (back-end thinking)

2. mvvm (front-end thinking)

Simple instructions

1.v-cloak

<div v-cloak>{ { msg }}</div>
Solve the flickering problem of interpolation expressions ({ {}} appearing when the page is refreshed and loaded.
$\color{red}{Note: matching style [v-cloak] {dislpay: none }}$
**

Do not parse tags

Only replace placeholders, do not overwrite the original content

2. v-text

<div v-text = "msg"></div>

No flicker problem by default

Override the content of the element

Do not parse tags

3.v-html

<div v-html= "msg"></div>

Overwrite the content of the element

Will parse tags

4.v-bind: (abbreviated as':')

<input type='button' v-bind:title='mytitle'></div>
Binding attributes, one-way data binding. When
v-bind is not added,'mytitle' is considered to be a string, and after it is added, it is a variable or legal js expression

5.v-on: (abbreviated'@')

Bound event

Click: v-on:click ='Method name' -------@click

Floating: v-on:mouseover ='method name' -------@mouseover

Leave: v-on:mouseout ='method name' -------@mouseout

Mobile touchstart, touchend, touchmove...

6. Event modifier

Written after the binding event name: such as @click.stop

.stop: stop bubbling

.prevent: Prevent default behavior

.capture: Change to event capture

.self: The event triggers a callback when the element itself is triggered

.once: trigger only once

7. Data two-way binding instruction v-model

<input type ='text' v-module = '属性名'>
$elements\color{red}{Note: Only applicable to form elements}$

8.v-for loop traversal

<p v-for = '(值, 索引) in 数组名/对象名' :key=''></p>

The value of key can only be srting or number type

Specify the key value in the form of binding attributes

9.v-if、v-show

<p v-if = '条件'></p>
<p v-show = '条件'></p>

v-if delete or create element

High switching performance consumption, if elements need to be switched frequently, v-if is not applicable

v-show hides or shows elements, which is equivalent to switching the display value =>'none'

There is a high initial rendering cost. If the element does not need to be displayed, v-show is not applicable

filter

Used as a common text formatting, it can be used in: mustache interpolation and v-bind expression;
{ {msg | filter name (passing parameter)}} ===> After processing the data through the filter, return Display the name;
'|' => pipe character; the
filter call adopts the principle of proximity, when the global filter and the private filter have the same name, the private filter is preferred;

1. Global filter

All vm instances are shared
Definition: Vue.filter('filter name', function(msg,arg){ //data processing})
Definition location: Define outside the vm instance
Parameters:

msg: the data before the pipe character

arg: received parameter

2. Private filter (partial)

Definition location: inside vm, filters: {}, at the same level
as methods Definition: filters:{ 过滤器名称(管道符前数据，接受的参数) {}}
"========="
(small knowledge): string.padStart(2, '0') is used to supplement the single digit zero

Custom instruction

The name of the custom command starts with'v-'

1. Overall

Definition: Vue.directive('Custom command?', {})
Parameter 1: When defining the command name, the custom command name is not prefixed with'v-', and
parameter 2: Object, there are some in the object Instruction related functions, perform corresponding operations at a specific stage
Example: focus event
<input type='text' v-focus>
Vue.directive('focus', {
每个函数第一个参数为 el，表示被绑定指令的元素，此时可使用原生的方法
	bind:function(el){ //指令绑定到元素上时执行，仅一次
		el.focus() //元素还未插入到DOM 中,不生效
		//多为与样式相关的操作
	}
	inserted:function(el){ //元素插入到 DOM 中的时候执行，仅一次
		el.focus() //元素已经插入到DOM 中，生效
		//多为与js相关的操作
	}
	updated:function(){ //VNode 更新时执行,可能触发多次

	}
})
Function related parameters

2. Private

Definition location: defined in the vm instance, at the same level
as methods Definition: directives: {'自定义指令名': {相关函数}}
function abbreviation (global/private):

Instance life cycle

Life cycle functions are at the same level as methods

**html:**
<div id='app'>
	<input type='button' value='改变msg' @click="msg='No'">
	<p id='p'>{
    
    { msg }}</p>
</div>
**js:**
var vm = new Vue({
	el: '#app',
	data: {
		msg: 'ok'
	},
	methods: {
		show() { console.log('执行了show方法') }
	},
})

***创建期间的生命周期函数***
beforCreate(){ //实例被完全创建之前执行
	//在这个生命周期内，data 和 methods 中的数据未初始化
	console.log(this.msg); //undefined
	this.show()  //报错，this.show() is not a function
}

created() {
	//在这个生命周期内，data 和 methods 中的数据初始化完成
	//可调用 methods 中的方法和操作 data 中的数据
	console.log(msg) //ok
	this.show() //执行了show方法
}

beforeMount() { //模板在内存中编译完成，还未渲染到页面中
	//在这个生命周期内，页面中的元素未被替换，还是原来写好的模板字符串
	console.log(document.getElementById('p').innerHtml) //{
    
    { msg }}
}

mounted() { 实例创建期间的最后一个生命周期函数
	//将编译好的内存中的模板挂在到页面中
	console.log(document.getElementById('p').innerHtml) //ok
}

***组件运行阶段的生命周期函数***
beforeUpdate() {  //界面还未被更新，但数据已被更新
	//组件/数据被改变时触发
	//例：当点击input按钮时：
	console.log(document.getElementById('p').innerHtml) // ok ===>页面未更新
	console.log(this.msg) // No ===>数据已经改变
}
undaated(){ //页面与数据都已更新
	//组件/数据被改变时触发
	//例：当点击input按钮时：
	console.log(document.getElementById('p').innerHtml) // No ===>页面已更新
	console.log(this.msg) // No ===>数据已经改变
}

***组件销毁阶段的生命周期函数***
beforeDestroy() {
	//还未执行销毁过程
}
destroyed() {
	//组件被完全销毁，此时组件中所有的数据、方法、指令、过滤器等 都不可用
}

Animation

Wrap the elements that need animation with tags.
Style:
v-enter, v-leave-to {} ——>Enter and leave
v-enter-active, v-leave-active {} ——>Intermediate process animation
Insert picture description here
Click to view: vue Animation detailed introduction

Components

Definition: Split the amount of code of the vue instance, divide different components into different functional modules, and call them when needed

1. Create globally

<div id='app'>
	<my-com1></my-com1>//引用组件
</div>
<template id='tmp1'>
	<div> //根元素
		<p>创建的组件</p>
	</div>
</template>

****Vue.component('组件名称', { //创建的组件模板对象 })****
Vue.component('myCom1', {
	template: '#tmp1'
}) 
注：
	1.若组件名称使用驼峰命名时，调用时用小写，并且单词之间‘-’连接，若未使用驼峰命名，则直接引用组件名；
	2.常见的模板对象必须有一个根元素包裹

2. Partial creation (private)

Inside the instance, at the same level as methods

components: { //定义实例内部私有组件
	组件名: {
		template: ''
	}
}

3. Data and methods in the component

Vue.compontent('com1', {
	template: '',
	data: function() {
		return {}
		//组件中的 data 为一个函数，且必须 return 一个对象
	},
	methods: {}
})

4. Component switching

<component :is="'组件名'"></component>

5. Component pass value

1. Father to Son

<div id='#app'>
	<com1 :parentmsg='msg' v-on:func='show'></com1>
</div>

<template id='son'>
	<div>
		<input type='button' value='点击调用父组件传递的方法' @click=‘parentfunc’>
		<p>子组件---{
    
    { parentmag }}</p>
	</div>
</template>

var vm = new Vue({
	el: '#app',
	data: {
		msg: '父组件数据'
	},
	methods: {
		show() {
			console.log('调用了父组件方法')
		}
	},
	//定义子组件：
	components: {
		com1: {
			template: '#son',
			props: ['parentmsg'], //将父组件传递的parentmsg属性在props数组中定义，然后才能使用，但是不做更改
			methods: {
				parentfunc() {
					this.$emit(‘func’)
				}
			}
		}
	}
})
总结：
	（1）在父组件调用子组件的地方，绑定一个自定义属性，属性值为要传递的数据，在子组件定义的地方通过props数组接收
	（2）若调用父组件的方法，在父组件调用子组件的地方，使用事件绑定方式，自定义事件名,在子组件的方法中，通过this.$emit('方法名')调用父组件方法

2. The child passes the parent
method to the parent component through the child component. The data to be passed to the parent component is returned as a parameter. In the parent component, the parameter is accepted when the method is called. If the passed is an object, it is in the parent component Define variable reception in data