el-date-picker在IE中赋值不成功

import moment from "moment";

<el-form-item prop="beginTime">
<el-date-picker
v-model="addForm.beginTime"
type="date"
size="medium"
:picker-options="pickerBeginDateBefore"
@change="changeTime"
>
</el-date-picker>

if(this.addForm.beginTime){

this.addForm.beginTime = moment(this.addForm.beginTime).format("l");

}

el-date-picker类型为date 后台返回数据为datetime 所以要对数据进行转换 我这里是使用的moment