<li v-for="(item,index) in assign" 
    :key="index"
    @click="selected(item)"
    :class="{‘active‘:item.isShow}">

selected(item) {
                if (!item.isShow) {
                    item.isShow = true;
                    this.selectedList.push(item.id)
                } else {
                    item.isShow = false;
                    let index = this.selectedList.indexOf(item.id);
                    if (index > -1) {
                        this.selectedList.splice(index, 1);
                    }
                }
            },
 

vue選中與取消簡單實現