<el-select v-model="value" placeholder="请选择"><el-optionv-for="item in cities":key="item.value":label="item.label":value="item.value"><el-tooltip class="item" :content="item.label" placement="right"><span>{{ item.label }}</span></el-tooltip></el-option>
</el-select><style>
.el-select-dropdown {width: 100px;
}
.el-select-dropdown__item {width:100%;overflow: hidden; text-overflow: ellipsis;white-space: nowrap;
}
</style>

data() {return {cities: [{value: 'Beijing',label: '北京北京北京北京北京北京北京'}, {value: 'Shanghai',label: '上海'}, {value: 'Nanjing',label: '南京'}, {value: 'Chengdu',label: '成都'}, {value: 'Shenzhen',label: '深圳'}, {value: 'Guangzhou',label: '广州'}],value: ''}
}