select，option变化，如果option不存在上次的选项，自动清空上次的选择
<script src="//unpkg.com/vue@2/dist/vue.js"></script>
<script src="//unpkg.com/element-ui@2.15.14/lib/index.js"></script>
<div id="app">
<template><el-select v-model="value" placeholder="请选择"><el-optionv-for="item in arr":key="item.value":label="item.label":value="item.value"></el-option></el-select><el-button @click="fun">fun</el-button><el-button @click="fun2">fun2</el-button><el-button @click="fun3">fun3</el-button><el-button @click="fun4">fun4</el-button>
</template>
</div>var Main = {data() {return {arr:[],options: [{value: '黄金糕',label: '黄金糕'}, {value: '双皮奶',label: '双皮奶'}, {value: '蚵仔煎',label: '蚵仔煎'}],options2: [{value: '黄金糕2',label: '黄金糕2'}, {value: '双皮奶2',label: '双皮奶2'}, {value: '蚵仔煎2',label: '蚵仔煎2'} ,{value: '蚵仔煎',label: '蚵仔煎'}],value: ''//}},methods:{fun(){this.arr= this.options},fun2(){this.arr=this.options2},fun3(){ this.arr=[]},fun4(){ alert(this.value)}},watch:{arr(val){let data=val.find(i=>i.value==this.value)if(!data)this.value=''}}}
var Ctor = Vue.extend(Main)
new Ctor().$mount('#app')
)
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)