@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);

                }

            }

        },

//组件

<el-select v-model="oil" @change="selected" placeholder="请选择">

    <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);

            },

重点：根据值查数组相同的元素