官网例子
<div class="block">
<span class="demonstration">hover 触发子菜单</span>
<el-cascader
v-model="value"
:options="options"
:props="{ expandTrigger: 'hover' }" 这样是不生效的@change="handleChange"></el-cascader>
br/>@change="handleChange"></el-cascader>
应该写成下面这样

<div class="block">
<span class="demonstration">hover 触发子菜单</span><el-cascader
expand-trigger="hover"
:options="options"
v-model="selectedOptions2"
@change="handleChange">
br/><el-cascader
expand-trigger="hover"
:options="options"
v-model="selectedOptions2"
@change="handleChange">
</div