计算属性关键词：computed
- 以下代码来说明methods方法和computed的区别
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Vue.js computed 属性练习</title>
<!-- 通过CDN引入Vue.js -->
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
<!-- vue-app的根容器 -->
<div id="app">
<button type="button" @click="show">调用methods点击</button>
<button type="button" @click="git()">调用computed点击</button>
</div>
<script type="text/javascript">
/* 实例化一个Vue对象 */
var app = new Vue({
el: '#app',
data: {
name1:'methods',
name2:'computed'
},
methods:{
show : function(){
alert(this.name1);
console.log(this.name1);
}
},
computed:{
git:function(){
alert(this.name2);
console.log(this.name2);
}
}
})
</script>
</body>
</html>
- 练习：购物车价格的计算
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Vue.js computed 属性练习-计算购物车总价</title>
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<!-- 通过CDN引入Vue.js -->
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<style type="text/css">
.container {
display: flex;
flex-direction: column;
}
.item {
display: flex;
border: 1px solid #7FFFD4;
border-radius: 0.625rem;
width: 90%;
margin: 0 auto;
height: 80px;
margin-bottom: 0.625rem;
/* 垂直方向居中 */
align-items: center;
/* 水平方向居中 */
/* justify-content: center; */
padding-left: 0.625rem;
padding-right: 0.625rem;
}
.item-id {
flex: 1 1 10%;
padding-left: 5px;
}
.item-ava{
flex: 1 1 10%;
}
.item-name {
flex: 1 1 30%;
}
.item-price {
flex: 1 1 10%;
padding-left:5px;
}
.item-count {
/* display: flex; */
flex: 1 1 30%;
padding-left: 50px;
}
.btn1{
background: white;
border: 1px solid #EEEEEE;
}
.goods-count {
width: 15px;
text-align: center;
margin-left: -5px;
margin-right: -5px;
border: none;
}
.total{
display: flex;
justify-content: space-between;
align-items: center;
}
.btn{
width: 20%;
background-color: #FF5000;
border-radius: 10px;
border: none;
outline: none;
color: #FFF;
font-size: 16px;
}
a:link{text-decoration: none; color: #333333;}
</style>
</head>
<body>
<!-- vue-app的根容器 -->
<div id="app">
<div class="container">
<div class="item" v-for="goods in goodsList">
<div class="item-id">
{{goods.id}}
</div>
<div class="item-ava">
<a v-bind:href="goods.url" ><img :src="goods.pic" width="30px" /></a>
</div>
<div class="item-name">
<a v-bind:href="goods.url">{{goods.name}}</a>
</div>
<div class="item-price">
{{goods.price}}
</div>
<div class="item-count">
<button type="button" @click="goods.count-=1" :disabled="goods.count==0" class="btn1">-</button>
<input type="text" class="goods-count" v-model="goods.count" />
<button type="button" @click="goods.count+=1" class="btn1">+</button>
<!-- <button type="button">详情</button> -->
</div>
</div>
<hr>
<div class="total">
<h3>总价： ￥{{totalPrice}}</h3>
<button type="button" class="btn" @click="sum()">结算</button>
</div>
<div class="result" v-if="show">
<p>你购买了{{sum}}件商品，共花费了{{totalPrice}}</p>
</div>
</div>
</div>
<script type="text/javascript">
/* 实例化一个Vue对象 */
var app = new Vue({
el: '#app',
data: {
goodsList: [{
id: 1,
pic:'https://img.alicdn.com/imgextra/i2/2616970884/O1CN01pvNZIP1IOucAsZA7a_!!2616970884.jpg_430x430q90.jpg',
name: 'iPhone 8',
price: 6000,
count: 1,
url:'https://item.taobao.com/item.htm?spm=a230r.1.14.15.235e6715yEMgmH&id=584799309331&ns=1&abbucket=4#detail'
},
{
id: 2,
pic:'https://img.alicdn.com/imgextra/i1/2653126415/O1CN01zDJQqZ1xG7FxE83iZ_!!0-item_pic.jpg_430x430q90.jpg',
name: 'innisfree',
price: 100,
count: 2,
url:'https://detail.tmall.hk/hk/item.htm?spm=a230r.1.14.6.4bb431d1ZJCgvU&id=555700146877&cm_id=140105335569ed55e27b&abbucket=4'
},
{
id: 3,
pic:'https://img.alicdn.com/imgextra/i3/479940663/O1CN011Glh2GGL4zFDOI2_!!479940663.jpg_430x430q90.jpg',
name: '童装',
price: 320,
count: 1,
url:'https://detail.tmall.com/item.htm?id=573629498709&ali_refid=a3_430583_1006:1103281714:N:%E9%A9%AC%E5%85%8Bjenny:ee00cf98898923c727825f2636c24d75&ali_trackid=1_ee00cf98898923c727825f2636c24d75&spm=a230r.1.14.1'
},
{
id: 4,
pic:'https://img.alicdn.com/imgextra/i1/2653126415/O1CN01zDJQqZ1xG7FxE83iZ_!!0-item_pic.jpg_430x430q90.jpg',
name: 'innisfree',
price: 500,
count: 1,
url:'https://detail.tmall.hk/hk/item.htm?spm=a230r.1.14.6.4bb431d1ZJCgvU&id=555700146877&cm_id=140105335569ed55e27b&abbucket=4'
}
],
show:false
},
methods: {
},
computed: {
totalPrice: function() {
//定义一个变量
var totalPrice = 0;
var len = this.goodsList.length;
for (var i = 0; i < len; i++) {
totalPrice += this.goodsList[i].price * this.goodsList[i].count;
}
return totalPrice;
},
sum:function(){
this.show = true;
var totalCount = 0;
var len = this.goodsList.length;
for (var i = 0; i < len; i++) {
totalCount += this.goodsList[i].count;
}
return totalCount;
}
}
})
</script>
</body>
</html>
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- 练习2- 搜索页面
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Vue.js computed 属性练习-搜索页面的实现</title>
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<!-- 通过CDN引入Vue.js -->
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<style type="text/css">
.container {
width: 90%;
margin: 0 auto;
}
.input-box {
width: 80%;
height: 30px;
margin-bottom: 15px;
display: flex;
}
.article {
display: flex;
height: 80px;
border: 1px solid #eee;
border-radius: 8px;
margin-bottom: 0.5rem;
}
.article-title {
flex: 1 1 50%;
}
.article-thumbnail {
flex: 1 1 30%;
}
.article-thumbnail img {
width: 100%;
height: 100%;
border-radius: 10px;
}
a:link {
text-decoration: none;
color: #333333;
}
.search-box{
width: 100%;
}
.search_btn {
outline: none;
width: 20%;
height: 30px;
margin-left: 10px;
background: white;
border: 1px solid #DDDDDD;
}
</style>
</head>
<body>
<!-- vue-app的根容器 -->
<div id="app">
<div class="container">
<div class="input-box">
<input type="text" v-model="searchString" placeholder="请输入搜索内容" class="search-box" />
<button type="button" class="search_btn" >搜索</button>
</div>
<div class="article" v-for="article in filteredArticles">
<a :href="article.url" class="article-title">
{{article.title}}
</a>
<div class="article-thumbnail">
<a :href="article.url"><img :src="article.image" /></a>
</div>
</div>
</div>
</div>
<script type="text/javascript">
var app = new Vue({
el: '#app',
data: {
searchString: "",
// 数据模型
articles: [{
"title": "堪称神器的3款在线工具，你一定用得上！",
"url": "https://www.jianshu.com/p/e83e7999346b",
"image": "https://img.haomeiwen.com/i11438996/56b25f32c9307b4b?imageMogr2/auto-orient/strip%7CimageView2/2/w/640/format/webp"
},
{
"title": "经典面试题：从 URL 输入到页面展现到底发生什么？",
"url": "https://www.jianshu.com/p/45ba3e0d0c7e",
"image": "https://img.haomeiwen.com/i3973862/d90954249a6f6ccd.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1000/format/webp"
},
{
"title": "如何免翻墙使用谷歌搜索和Chrome应用商店",
"url": "https://www.jianshu.com/p/484f8e6c88f6",
"image": "https://img.haomeiwen.com/i858154/015a4b083685a3d1.jpg?imageMogr2/auto-orient/strip%7CimageView2/2/w/800/format/webp"
},
{
"title": "四款前所未有好用的黑科技APP，绝对的良心实用，赶紧告诉家人",
"url": "https://www.jianshu.com/p/2aec84d269fe",
"image": "https://img.haomeiwen.com/i16042993/168b2cb17fd7ec0c?imageMogr2/auto-orient/strip%7CimageView2/2/w/640/format/webp"
},
{
"title": "坚持学英语的方法有哪些",
"url": "https://www.jianshu.com/p/0a6a61b0933c",
"image": "https://img.haomeiwen.com/i3525704/c7293758fc59e56b.jpg?imageMogr2/auto-orient/strip%7CimageView2/2/w/960/format/webp"
}
]
},
computed: {
// 计算函数，匹配搜索
filteredArticles: function() {
var articles_array = this.articles,
searchString = this.searchString;
//搜索关键词为空,则返回原始数据集
if (!searchString) {
return articles_array;
}
//搜索关键词去除无用空格,转换为小写
searchString = searchString.trim().toLowerCase();
//过滤数组中每个元素,如果
articles_array = articles_array.filter(function(item) {
if (item.title.toLowerCase().indexOf(searchString) !== -1) {
return item;
}
})
// 返回转化后的数组
return articles_array;;
}
}
})
</script>
</body>
</html>
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