Change事件多參

@change="(value) => selected(value, item)"

selected(val, item) {
    if (val === true) {
            this.selectedData.push(item.courseware_id)
        } else {
           let index = this.selectedData.indexOf(item.courseware_id);
            if (index > -1) {
                this.selectedData.splice(index, 1);
                }
            }
        },

//組件
<el-select v-model="oil" @change="selected" placeholder="請選擇">
    <el-option
        v-for="item in treeList"
            :key="item.id"
            :label="item.name"
            :value="item.id"
        >
    </el-option>
</el-select>

//js                            
                            
selected(val) {
                let data = this.treeList.find(item => {
                    if (item.id === val) {
                        return item
                    }
                });
                console.log(data);
            },
            
重點：根據值查數組相同的元素