The content of this article is about the analysis of the 4-v-bind instruction (with code). It has a good reference value and I hope it can help friends in need.
1. Definition
1.1 The v-bind directive is used to update HTML attributes responsively. In fact, it supports a single JavaScript expression (except v-for).
2. Grammar
2.1 Complete syntax: , explanation: v-bind is an instruction, followed by : The class is a parameter, and classProperty is called the "expected value" in the official documentation.
2.2 Abbreviation syntax: , explanation:: The following class is a parameter, and classProperty is called "expected value" in the official documentation .
3. Usage
3.1 Bind a property
Full code example:
<template><p>
</p>
<p>{{title}}</p>
<span>{{text}}</span></template><script>
export default {
name: "v-bindLearn",
data() { return {
title: "v-bind学习",
first: "span1",
text: "绑定一个属性"
}
}
}</script><style>
.p1{
text-align: left;
}
.spancss1{
float: left;
}</style>Copy after login
Abbreviated code example: 
<template>
<div>
<p class="p1">{{title}}</p>
<span :value="first" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
first: "span1",
text: "绑定一个属性"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
3.2 Inline string concatenation code example
<template>
<div>
<p class="p1">{{title}}</p>
<a :href="'http://'+first" class="spancss1">{{text}}</a>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
first: "www.baidu.com",
text: '点击跳转到百度链接'
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
3.3 class binding
3.3.1 Object syntax
Span tag binds an object
The method is to declare the object directly in the template, declare the attributes prop1 and prop2 in the object, and declare whether the attributes are output in javascript Available. If the declared attribute value is set to true, the declared attribute value is available. If the declared attribute value is set to false, the declared attribute value is unavailable. The code is as follows:
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:class="{prop1:isTrue,prop2:isActive}" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
isTrue: false,
isActive: true,
text: "对象语法1"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
Method 2 directly declares the object name in the template, declares the attributes prop1 and prop2 in javascript and outputs whether they are available. If the declared attribute value is set to true, the declared attribute value is available. If the declared attribute value is set to false , then the declared attribute value is unavailable, the code is as follows: 
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:class="obj" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
obj: {
prop1: true,
prop2: false
},
text: "对象语法2"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
##3.3.2 Array syntax
method always declares the array name directly in the template, Output the required array elements in javascript. The sample code is as follows:
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:class="arr" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
arr: ['prop1','prop2','prop3'],
text: "数组语法1"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
Method 2: Declare the array in the template and define its elements, and output the array in javascript to define whether the elements are available. , if you need to use this array element, define in javascript to output the attribute value of the corresponding array element. If you do not need to use this array element, set the attribute value of this array element to false. The sample code is as follows:
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:class="[prop1,prop2,prop3]" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
prop1: 'prop1',
prop2: false,
prop3: 'prop3',
text: "数组语法2"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
Method three switches the bound class in the list based on conditions, declares the array and conditional expression in the template, and outputs the value of the conditional expression of the array element in JavaScript. The sample code is as follows:
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:class="[prop1?'prop1':'',prop2,prop3?'prop3':'',prop4?'prop4':'prop5',prop6?'prop6':'prop5']" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
prop1: false,
prop2: 'prop2',
prop3: true,
prop4: true,
prop6: false,
text: "数组语法3"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
3.4 Binding inline styles
3.4.1 Object syntax, declare attributes in template, output corresponding attribute values in javascript, sample code As follows:
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:style="{background:color1,fontSize:fontSize+'px'}" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
color1: 'green',
fontSize: 25,
text: "绑定内联样式1"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
3.4.2 Array syntax, multiple style objects can be applied to the same element
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:style="[prop1,prop2]" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
prop1: {
background:'green'
},
prop2: {
fontSize: '25px',
fontWeight: 'bolder'
},
text: "绑定内联样式1"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
3.4.3 When v-bind:style uses CSS properties that require adding a browser engine prefix, such as transform, Vue.js will automatically detect and add the corresponding prefix.
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:style="[prop1,prop2]" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
prop1: {
background:'green'
},
prop2: {
fontSize: '25px',
transform: 'rotate(7deg)'
},
text: "绑定内联样式1"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
3.4.4 Multiple value binding, starting from 2.3.0 you can provide an array containing multiple values for the attribute in style binding, which is often used to provide Multiple prefixed values, if the browser supports flexbox without browser prefix, then only display: flex
<template>
<div>
<p class="p1">{{title}}</p>
<span v-bind:style="{ display: ['-webkit-box', '-ms-flexbox', 'flex'] }" class="spancss1">{{text}}</span>
</div>
</template>
<script>
export default {
name: "v-bindLearn",
data() {
return {
title: "v-bind学习",
text: "绑定内联样式4"
}
}
}
</script>
<style scoped>
.p1{
text-align: left;
}
.spancss1{
float: left;
}
</style>Copy after login
Summary: v-bind dynamically binds one or more features, or a component prop to an expression, which can easily render DOM
Related recommendations:
The initial construction process of the project in Vue (picture and text)
Analysis of the directory structure after Vue-cli builds the project (picture and text)
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