11 计算属性和过滤器

作者: 孙嘉炜 | 来源:发表于2019-04-18 09:17 被阅读0次

1.methods和computed的区别

如以下代码：computed1.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>计算</title>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
<div id="app">
<button type="button" @click="show1()">调用methods方法点击</button>
<button type="button" @click="show2()">调用computer方法点击</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:{
show1:function(){
/ console.log(this.name1); */
alert(this.name1);
}
},
computed:{
show2:function(){
alert(this.name2);
}
}
})
</script>
</body>
</html>

运行结果：

image

2.购物车:computed.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Vue.js computed练习——计算购物车总价</title>
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">

<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<style type="text/css">

        header{
            background: #FF7F50;
            width: 100%;
            height: 120px;
            color: #EEEEEE;
            left: 20px;
        }
        .container{
            left: 10px;
            position: relative;
            top: -20px;
            display: flex;
            flex-direction: column;
        }
        .item{
            display: flex;
            border: 1px solid #008000;
            border-radius: 10px;
            width: 85%;
            height: 50px;
            margin-bottom: 10px;
            /* 垂直方向居中 */
            align-items: center;
            /* 水平方向居中 */
            /* justify-content: center; */
            /* 内边距 */
            padding-left: 10px;
            padding-right: 10px;
            background: #EEEEEE;
        }
        .item-id{
            flex: 1 1 20%;
        }
        .item-name{
            flex: 1 1 20%;
        }
        .item-price{
            flex: 1 1 20%;
        }
        .item-count{
            flex: 1 1 20%;
        }
        .goods-count{
            width: 15px;
            text-align: center;
        }
        .accounts{
            display: flex;
            position: absolute;
            background: #FF7F50;
            width: 60px;
            height: 40px;
            /* 垂直方向居中 */
            align-items: center;
            border: 1px #008000;
            border-radius: 10px;
            left: 270px;
            top: 220px;
            outline:none;
            justify-content: center;
        }
        .totle{
            position: relative;
            top: -55px;
            left: 100px;
        }
        #photo{
            position: relative;
            width: 40px;
            height: 40px;
            left: 15px; 
        }
        .settlement {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        .btn {
            width: 100px;
            height: 40px;
            background-color: #FF5000;
            border-radius: 10px;
            border: none;
            outline: none;
            color: #FFF;
            font-size: 16px;
        }
    </style>
</head>
<body>
    <header>
        <h3>购物车</h3>
        <p>共3件宝贝</p>
    </header>
    <!-- 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}}
                    <img :src="goods.photo" id="photo"/>
                </div>
                <div class="item-name">
                    {{goods.name}}
                </div>
                <div class="item-price">
                    {{goods.price}}
                </div>
                <div class="item-count">
                    <!--  :disabled="goods.count===0"减到0不能再减了-->
                    <button type="button" @click="goods.count-=1" :disabled="goods.count===0">-</button>
                    <input type="text" v-model="goods.count" class="goods-count"/>
                    <button type="button" @click="goods.count+=1">+</button>
                </div>
            </div>
            <hr >
            <!-- <h3>Total price:</h3>
            <p class="totle">￥{{totalPrice}}</p>
            <button class="accounts">结算</button> -->
            <div class="settlement">
                <h3>总价：￥{{totalPrice}}</h3>
                <button type="button" class="btn" @click="settlement()">结算</button>
            </div>
            <div class="result" v-if="show">
                你购买了{{settlement}}件商品，需要支付总价为：{{totalPrice}}元
            </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,
                        name:'iphone 8',
                        price:6000,
                        count:1,
                        photo:'img/xphone.jpg'
                    },
                    {
                        id:2,
                        name:'iphone X',
                        price:7000,
                        count:2,
                        photo:'img/iphone2.jpg'
                    },
                    {
                        id:3,
                        name:'iphone XS Max',
                        price:8000,
                        count:1,
                        photo:'img/iphone3.jpg'
                    }
                ],
                show:false
            },
            methods:{
            },
            computed:{
                totalPrice:function(){
                    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;
            },
                    settlement: 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>

运行结果：

image

3.搜索按钮进行页面搜索：computed.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Vue.js computed练习-搜索页面的实现</title>
<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: 50%;
            height: 25px;
            margin-bottom: 10px;
        }

        .item {
            display: flex;
            height: 100px;
            border: 1px solid #eee;
            border-radius: 8px;
            margin-bottom: 8px;
        }

        .item-title {
            flex: 1 1 80%;
            color: #00FFFF;
        }

        .item-thumbnail {
            flex: 1 1 20%;
        }

        .item-thumbnail img {
            width: 100%;
            height: 100%;
        }

        a {
            text-decoration: none;
        }

        a:link {
            color: #8E8E8E;
            text-decoration: underline;
        }

        a:visited {
            color: #008000;
            text-decoration: none;
        }

        a:hover {
            color: #0000FF;
            text-decoration: none;
        }

        a:active {
            color: #FF7F50;
            text-decoration: none;
        }

        .search {
            position: relative;
            top: -41px;
            width: 60px;
            height: 32px;
            background: #7FFF00;
            left: 50%;
            margin-bottom: 10px;
            /* 垂直方向居中 */
            align-items: center;
            display: flex;
            border: 1px solid #DDDDDD;
            outline: none;
        }
    </style>
</head>
<body>
    <div id="app">
        <div class="container">
            <input type="text" v-model="searchString" placeholder="请输入" class="input-box" />

            <button class="search" @click="handleClick()">搜索</button>

            <div class="item" v-for="article in filteredArticles" v-show="show">

                <a :href="article.url" class="item-title">
                    {{article.title}}
                </a>
                <div class="item-thumbnail">
                    <img :src="article.image">
                </div>
            </div>
        </div>
    </div>
    <script type="text/javascript">
        var app = new Vue({
            el: '#app',
            data: {
                searchString: "",
                show: false,
                // 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;
                }
            },
            methods: {
                handleClick: function() {
                    this.show = true;
                }
            },
        })
    </script>
</body>

</html>

运行结果：

image

搜索按钮可以按，但是刚开始没有主页面，这个好像是一次性的。

form表单练习：form.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Vue.js表单练习</title>

<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
<div id="app">
<input v-model="message1" placeholder="编辑我……">
<p>输入内容是: {{ message1 }}</p>

<textarea v-model="message2" placeholder="多行文本输入……"></textarea>
<p>多行文本域内容是：{{ message2 }}</p>

<input type="checkbox" id="baidu" value="BAIDU" v-model="checkedNames">
<label for="baidu">百度</label>
<input type="checkbox" id="google" value="GOOGLE" v-model="checkedNames">
<label for="google">谷歌</label>
<input type="checkbox" id="tencent" value="TENTCENT" v-model="checkedNames">
<label for="tencent">腾讯</label>

<span>选择的值为: {{ checkedNames }}</span>

<label>你一共选了{{checkedNames.length}}个</label>

<input type="radio" id="male" value="male" v-model="picked">
<label for="male">男</label>

<input type="radio" id="female" value="female" v-model="picked">
<label for="female">女</label>

<span>选中值为: {{ picked }}</span>

<select v-model="selected" name="fruit">
<option value="">选择一个网站</option>
<option value="www.baidu.com">百度</option>
<option value="www.taobao.com">淘宝</option>
<option value="www.niit.edu.cn">南工院</option>
</select>

<p> 选择的网站是: {{selected}}</p>

<button type="button" @click="commit">提交</button>
<hr >
<h2>结果显示</h2>
<div class="result">
<p>姓名：{{message1}}</p>
<p>性别：{{picked}}</p>
<h3>爱好</h3>
<ul>
<li v-for="item in checkedNames">
{{item}}
</li>
</ul>
<p>班级：{{selected}}</p>
</div>
</div>

    <script type="text/javascript">
        var app = new Vue({
            el: '#app',
            data: {
                message1: 'Hello Vue',
                message2: 'Vue官方教程',
                checkedNames: [],
                picked: 'male',
                selected: ''
            },
            methods: {
                commit: function() {
                    alert(this.message1 + this.picked + this.selected);
                }
            }
        })
    </script>
</body>

</html>

运行结果：

image

11 计算属性和过滤器

1.methods和computed的区别

2.购物车:computed.html

3.搜索按钮进行页面搜索：computed.html

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