How to use template syntax and vue instructions in Vue3

1 Template interpolation syntax

• Declaring a variable in script can be used directly in template using {{variable name}}

• template The syntax is that you can write conditional operations

• Operations are also supported

• Operation API is also supported

<template>
  {{ message }}
    {{ message2==0 ? &#39;我是老大&#39; : &#39;我笑的&#39; }}
    {{ message2 + 1 }}
    {{ message.split(&#39;&#39;).map(v => `4546$v`) }}
</template>

<script setup lang="ts">
const message = "我是唐少"
const message2:number = 1
</script>
<style>
</style>

2 Instructions

• v- Instructions starting with vue

• v-text is used to display text

• v-html is used to display rich text

• v-if is used to control the display and hiding of elements (switching true and false DOM)

• v-else-if represents the "else if block" of v-if. Can be called in a chain

• v-else v-if conditional ending statement

• v-show is used to control the display and hiding of elements (display none block Css switch)

• v-on abbreviation @ is used to add events to elements

• v-bind abbreviation: is used to bind elements Attribute Attr

• v-model two-way binding

• v-for is used to traverse elements

v-on modifier

Bubble case:

<template>
  <div @click="parent">parent
    <div @click.stop="child">child</div>
  </div>
</template>
  
<script setup lang="ts">
const child = () => {
  console.log(&#39;child&#39;);
 // 点击后不会答应parent，因为被阻止了
}
const parent = () => {
  console.log(&#39;parent&#39;);
}
  
</script>

Prevent form submission case:

<template>
  <form action="/">
    <button @click.prevent="submit" type="submit">submit</button>
  </form>
</template>
<script setup lang="ts">
const submit = () => {
  console.log(&#39;child&#39;);
  
}
</script>
<style>
</style>

v-bind binding class Case 1:

<template>
  <div :class="[flag ? &#39;active&#39; : &#39;other&#39;, &#39;h&#39;]">456789</div>
</template>
<script setup lang="ts">
const flag: boolean = false;// 改成true后切换不同的效果
</script>
  
<style>
.active {
  color: red;
}
.other {
  color: blue;
}
.h {
  height: 300px;
  border: 1px solid #ccc;
}
</style>

v-bind binding class case 2:

<template>
  <div :class="flag">{{flag}}</div>
</template>
 // 直接绑定cls
<script setup lang="ts">
type Cls = {
  other: boolean,
  h: boolean
}
const flag: Cls = {
  other: false,
  h: true
};
</script>
<style>
.active {
  color: red;
}
.other {
  color: blue;
}
.h {
  height: 300px;
  border: 1px solid #ccc;
}
</style>

v-bind binding style case:

<template>
  <div :>绑定style</div>
</template>
<script setup lang="ts">
type Style = {
  height: string,
  color: string
}
const style: Style = {
  height: "300px",
  color: "blue"
}
</script>
<style>
</style>

v-model case:

<template>
  <input v-model="message" type="text" />
  <div>{{ message }}</div>
</template>
<script setup lang="ts">
import { ref } from &#39;vue&#39; // 实时监听
const message = ref("message")
</script>
  
<style>
.active {
  color: red;
}
.other {
  color: blue;
}
.h {
  height: 300px;
  border: 1px solid #ccc;
}
</style>

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