1.computed是在HTML DOM加载后马上执行的，如赋值；
2.methods则必须要有一定的触发条件才能执行，如点击事件；
3.watch呢？它用于观察Vue实例上的数据变动。对应一个对象，键是观察表达式，值是对应回调。值也可以是方法名，或者是对象，包含选项。
所以他们的执行顺序为：默认加载的时候先computed再watch，不执行methods；等触发某一事件后，则是：先methods再watch。
4.mounted是生命周期
5.created和mounted区别？
我们从图中看两个节点：
created:在模板渲染成html前调用，即通常初始化某些属性值，然后再渲染成视图。
mounted:在模板渲染成html后调用，通常是初始化页面完成后，再对html的dom节点进行一些需要的操作。
其实两者比较好理解，通常created使用的次数多，而mounted通常是在一些插件的使用或者组件的使用中进行操作，比如插件chart.js的使用: var ctx = document.getElementById(ID);通常会有这一步，而如果你写入组件中，你会发现在created中无法对chart进行一些初始化配置，一定要等这个html渲染完后才可以进行，那么mounted就是不二之选。下面看一个例子（用组件）。
我们用下面的例子再解说解说这些关系
HTML
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width,initial-scale=1.0"> <title>my-vue</title> <style> body{ font-family:"Microsoft YaHei"; } #tab{ width: 600px; margin: 0 auto; } .tab-tit{ font-size: 0; width: 600px; } .tab-tit a{ display: inline-block; height: 40px; line-height: 40px; font-size: 16px; width: 25%; text-align: center; background: #ccc; color: #333; text-decoration: none; } .tab-tit .cur{ background: #09f; color: #fff; } .tab-con div{ border: 1px solid #ccc; height: 400px; padding-top: 20px; } .fl{ float: left; } .fr{ float: right; } blockquote, body, dd, div, dl, dt, fieldset, form, h1, h2, h3, h4, h5, h6, img, input, li, ol, p, table, td, textarea, th, ul { margin: 0; padding: 0; } .clearfix{ zoom: 1; } .clearfix:after { clear: both; } .clearfix:after { content: '.'; display: block; overflow: hidden; visibility: hidden; font-size: 0; line-height: 0; width: 0; height: 0; } a{ text-decoration: none; color: #333; } img{vertical-align: middle;} .page-shopping-cart { width: 1200px; margin: 50px auto; font-size: 14px; border: 1px solid #e3e3e3; border-top: 2px solid #317ee7; } .page-shopping-cart .cart-title { color: #317ee7; font-size: 16px; text-align: left; padding-left: 20px; line-height: 68px; } .page-shopping-cart .red-text { color: #e94826; } .page-shopping-cart .check-span { display: block; width: 24px; height: 20px; background: #fff; border: 1px solid #ccc; } .page-shopping-cart .check-span.check-true { background:#00f; } .page-shopping-cart .td-check { width: 70px; } .page-shopping-cart .td-product { width: 460px; } .page-shopping-cart .td-num, .page-shopping-cart .td-price, .page-shopping-cart .td-total { width: 160px; } .page-shopping-cart .td-do { width: 150px; } .page-shopping-cart .cart-product-title { text-align: center; height: 38px; line-height: 38px; padding: 0 20px; background: #f7f7f7; border-top: 1px solid #e3e3e3; border-bottom: 1px solid #e3e3e3; } .page-shopping-cart .cart-product-title .td-product { text-align: center; font-size: 14px; } .page-shopping-cart .cart-product-title .td-check { text-align: left; } .page-shopping-cart .cart-product-title .td-check .check-span { margin: 9px 6px 0 0; } .page-shopping-cart .cart-product { padding: 0 20px; text-align: center; } .page-shopping-cart .cart-product table { width: 100%; text-align: center; font-size: 14px; } .page-shopping-cart .cart-product table td { padding: 20px 0; } .page-shopping-cart .cart-product table tr { border-bottom: 1px dashed #e3e3e3; } .page-shopping-cart .cart-product table tr:last-child { border-bottom: none; } .page-shopping-cart .cart-product table .product-num { border: 1px solid #e3e3e3; display: inline-block; text-align: center; } .page-shopping-cart .cart-product table .product-num .num-do { width: 24px; height: 28px; display: block; background: #f7f7f7; } .page-shopping-cart .cart-product table .product-num .num-reduce span { background: url("shopping_cart.png") no-repeat -40px -22px; display: block; width: 6px; height: 2px; margin: 13px auto 0 auto; } .page-shopping-cart .cart-product table .product-num .num-add span { background: url("shopping_cart.png") no-repeat -60px -22px; display: block; width: 8px; height: 8px; margin: 10px auto 0 auto; } .page-shopping-cart .cart-product table .product-num .num-input { width: 42px; height: 28px; line-height: 28px; border: none; text-align: center; } .page-shopping-cart .cart-product table .td-product { text-align: left; font-size: 12px; line-height: 20px; } .page-shopping-cart .cart-product table .td-product img { border: 1px solid #e3e3e3; margin-right: 10px; } .page-shopping-cart .cart-product table .td-product .product-info { display: inline-block; vertical-align: middle; } .page-shopping-cart .cart-product table .td-do { font-size: 12px; } .page-shopping-cart .cart-product-info { height: 50px; line-height: 50px; background: #f7f7f7; padding-left: 20px; } .page-shopping-cart .cart-product-info .delect-product { color: #666; } .page-shopping-cart .cart-product-info .delect-product span { display: inline-block; vertical-align: top; margin: 18px 8px 0 0; width: 13px; height: 15px; background: url("shopping_cart.png") no-repeat -60px 0; } .page-shopping-cart .cart-product-info .product-total { font-size: 14px; color: #e94826; } .page-shopping-cart .cart-product-info .product-total span { font-size: 20px; } .page-shopping-cart .cart-product-info .check-num { color: #333; } .page-shopping-cart .cart-product-info .check-num span { color: #e94826; } .page-shopping-cart .cart-product-info .keep-shopping { color: #666; margin-left: 40px; } .page-shopping-cart .cart-product-info .keep-shopping span { display: inline-block; vertical-align: top; margin: 18px 8px 0 0; width: 15px; height: 15px; background: url("shopping_cart.png") no-repeat -40px 0; } .page-shopping-cart .cart-product-info .btn-buy { height: 50px; color: #fff; font-size: 20px; display: block; width: 110px; background: #ff7700; text-align: center; margin-left: 30px; } .page-shopping-cart .cart-worder { padding: 20px; } .page-shopping-cart .cart-worder .choose-worder { color: #fff; display: block; background: #39e; width: 140px; height: 40px; line-height: 40px; border-radius: 4px; text-align: center; margin-right: 20px; } .page-shopping-cart .cart-worder .choose-worder span { display: inline-block; vertical-align: top; margin: 9px 10px 0 0; width: 22px; height: 22px; background: url("shopping_cart.png") no-repeat -92px 0; } .page-shopping-cart .cart-worder .worker-info { color: #666; } .page-shopping-cart .cart-worder .worker-info img { border-radius: 100%; margin-right: 10px; } .page-shopping-cart .cart-worder .worker-info span { color: #000; } .choose-worker-box { width: 620px; background: #fff; } .choose-worker-box .box-title { height: 40px; line-height: 40px; background: #F7F7F7; text-align: center; position: relative; font-size: 14px; } .choose-worker-box .box-title a { display: block; position: absolute; top: 15px; right: 16px; width: 10px; height: 10px; background: url("shopping_cart.png") no-repeat -80px 0; } .choose-worker-box .box-title a:hover { background: url("shopping_cart.png") no-repeat -80px -22px; } .choose-worker-box .worker-list { padding-top: 30px; height: 134px; overflow-y: auto; } .choose-worker-box .worker-list li { float: left; width: 25%; text-align: center; margin-bottom: 30px; } .choose-worker-box .worker-list li p { margin-top: 8px; } .choose-worker-box .worker-list li.cur a { color: #f70; } .choose-worker-box .worker-list li.cur a img { border: 1px solid #f70; } .choose-worker-box .worker-list li a:hover { color: #f70; } .choose-worker-box .worker-list li a:hover img { border: 1px solid #f70; } .choose-worker-box .worker-list li img { border: 1px solid #fff; border-radius: 100%; } .check-true{ background:#00f; } </style> </head> <body> <div id="tab"> <div class="tab-tit"> <!--点击设置curId的值 如果curId等于0，第一个a添加cur类名，如果curId等于1，第二个a添加cur类名，以此类推。添加了cur类名，a就会改变样式 @click,:class ,v-show这三个是vue常用的指令或添加事件的方式--> <a href="javascript:;" @click="curId=0" :class="{'cur':curId===0}">html</a> <a href="javascript:;" @click="curId=1" :class="{'cur':curId===1}">css</a> <a href="javascript:;" @click="curId=2" :class="{'cur':curId===2}">javascript</a> <a href="javascript:;" @click="curId=3" :class="{'cur':curId===3}">vue</a> </div> <div class="tab-con"> <!--根据curId的值显示div,如果curId等于0，第一个div显示，其它三个div不显示。如果curId等于1，第二个div显示，其它三个div不显示。以此类推--> <div v-show="curId===0"> html<br/> </div> <div v-show="curId===1"> css </div> <div v-show="curId===2"> javascript </div> <div v-show="curId===3"> vue </div> </div> </div> <div class="page-shopping-cart" id="shopping-cart"> <h4 class="cart-title">购物清单</h4> <div class="cart-product-title clearfix"> <div class="td-check fl"><span class="check-span fl check-all" :class="{'check-true':isSelectAll}" @click="selectProduct(isSelectAll)"></span>全选</div> <div class="td-product fl">商品</div> <div class="td-num fl">数量</div> <div class="td-price fl">单价(元)</div> <div class="td-total fl">金额(元)</div> <div class="td-do fl">操作</div> </div> <div class="cart-product clearfix"> <table> <tbody> <!--遍历的时候带上索引--> <tr v-for="(item,index) in productList"> <td class="td-check"><span class="check-span" @click="item.select=!item.select" :class="{'check-true':item.select}"></span></td> <td class="td-product"><img :src="item.pro_img" width="98" height="98"> <div class="product-info"> <h6>{{item.pro_name}}</h6> <p>品牌：{{item.pro_brand}} 产地：{{item.pro_place}}</p> <p>规格/纯度:{{item.pro_purity}} 起定量：{{item.pro_min}}</p> <p>配送仓储：{{item.pro_depot}}</p> </div> <div class="clearfix"></div> </td> <td class="td-num"> <div class="product-num"> <a href="javascript:;" class="num-reduce num-do fl" @click="item.pro_num>0?item.pro_num--:''"><span>-</span></a> <input type="text" class="num-input" v-model="item.pro_num"> <a href="javascript:;" class="num-add num-do fr" @click="item.pro_num++"><span>+</span></a> </div> </td> <td class="td-price"> <p class="red-text">￥<span class="price-text">{{item.pro_price.toFixed(2)}}</span></p> </td> <td class="td-total"> <p class="red-text">￥<span class="total-text">{{item.pro_price*item.pro_num}}</span>.00</p> </td> <td class="td-do"><a href="javascript:;" class="product-delect" @click="deleteOneProduct(index)">删除</a></td> </tr> </tbody> </table> </div> <div class="cart-product-info"> <a class="delect-product" href="javascript:;" @click="deleteProduct"><span></span>删除所选商品</a> <a class="keep-shopping" href="#"><span></span>继续购物</a> <a class="btn-buy fr" href="javascript:;">去结算</a> <p class="fr product-total">￥<span>{{getTotal.totalPrice}}</span></p> <p class="fr check-num"><span>{{getTotal.totalNum}}</span>件商品总计（不含运费）：</p> </div> </div> </body> </html>
JS
// The Vue build version to load with the `import` command // (runtime-only or standalone) has been set in webpack.base.conf with an alias. import Vue from 'vue' import App from './App' import router from './router' Vue.config.productionTip = false /* eslint-disable no-new */ new Vue({ el: '#tab', data: { curId: 0 }, computed: {}, methods: {}, mounted: function () { } }) new Vue({ el: '#shopping-cart', data: { productList: [ { 'pro_name': '【斯文】甘油 | 丙三醇',//产品名称 'pro_brand': 'skc',//品牌名称 'pro_place': '韩国',//产地 'pro_purity': '99.7%',//规格 'pro_min': "215千克",//最小起订量 'pro_depot': '上海仓海仓储',//所在仓库 'pro_num': 3,//数量 'pro_img': '../../images/ucenter/testimg.jpg',//图片链接 'pro_price': 800//单价 }, { 'pro_name': '【斯文】甘油 | 丙三醇',//产品名称 'pro_brand': 'skc',//品牌名称 'pro_place': '韩国',//产地 'pro_purity': '99.7%',//规格 'pro_min': "215千克",//最小起订量 'pro_depot': '上海仓海仓储',//所在仓库 'pro_num': 3,//数量 'pro_img': '../../images/ucenter/testimg.jpg',//图片链接 'pro_price': 800//单价 }, { 'pro_name': '【斯文】甘油 | 丙三醇',//产品名称 'pro_brand': 'skc',//品牌名称 'pro_place': '韩国',//产地 'pro_purity': '99.7%',//规格 'pro_min': "215千克",//最小起订量 'pro_depot': '上海仓海仓储',//所在仓库 'pro_num': 3,//数量 'pro_img': '../../images/ucenter/testimg.jpg',//图片链接 'pro_price': 800//单价 } ] }, computed: { //检测是否全选 isSelectAll:function(){ //如果productList中每一条数据的select都为true，返回true，否则返回false; return this.productList.every(function (val) { return val.select}); }, //获取总价和产品总件数 getTotal:function(){ //获取productList中select为true的数据。 var _proList=this.productList.filter(function (val) { return val.select}),totalPrice=0; for(var i=0,len=_proList.length;i<len;i++){ //总价累加 totalPrice+=_proList[i].pro_num*_proList[i].pro_price; } //选择产品的件数就是_proList.length，总价就是totalPrice return {totalNum:_proList.length,totalPrice:totalPrice} } }, methods: { //全选与取消全选 selectProduct:function(_isSelect){ //遍历productList，全部取反 for (var i = 0, len = this.productList.length; i < len; i++) { this.productList[i].select = !_isSelect; } }, //删除已经选中(select=true)的产品 deleteProduct:function () { this.productList=this.productList.filter(function (item) {return !item.select}) }, //删除单条产品 deleteOneProduct:function (index) { //根据索引删除productList的记录 this.productList.splice(index,1); }, }, mounted: function () { var _this=this; //为productList添加select（是否选中）字段，初始值为true this.productList.map(function (item) { _this.$set(item, 'select', true); }) } })