js 递归处理数据之每个层级下子集累计某个参数求和

场景：现需要一个树形数据，计算出每个层级下，子集中某个参数的累加和

let nodes= [
            {
                title: '顶顶顶顶',
                key: '0-0',
                num: 0,
                expanded: true,
                children: [
                    {
                        title: '啊啊啊啊',
                        key: '0-0-0',
                        num: 100,
                        checked: true,
                        isLeaf: true,
                    },
                    {
                        title: '大大大',
                        key: '0-0-1',
                        checked: true,
                        isLeaf: true,
                        num: 100,
                    },
                ]
            },
            {
                title: '反反复复',
                key: '0-1',
                num: 0,
                children: [
                    {
                        title: '灌灌灌灌',
                        num: 100,
                        key: '0-1-0-0',
                        checked: true,
                        isLeaf: true
                    },
                    {
                        title: '呜呜呜呜',
                        num: 100,
                        key: '0-2-0-0',
                        checked: false,
                        isLeaf: true
                    },
                ]
            }
        ];
 changeTreeData(nodes: any): void {
        nodes.forEach((item: any) => {
            if (item.children) {
                item.children = this.changeTreeData(item.children);
                item.num = 0;
                item.children.forEach((elm: any) => {
                     item.num += elm.num;
                })
             
            }
        })
        return nodes;
    }
this.changeTreeData(nodes);

场景二：同场景1需求，附加仅支持勾选复选框的累加

let nodes= [
            {
                title: '顶顶顶顶',
                key: '0-0',
                num: 0,
                expanded: true,
                children: [
                    {
                        title: '啊啊啊啊',
                        key: '0-0-0',
                        num: 100,
                        checked: true,
                        isLeaf: true,
                    },
                    {
                        title: '大大大',
                        key: '0-0-1',
                        checked: true,
                        isLeaf: true,
                        num: 100,
                    },
                ]
            },
            {
                title: '反反复复',
                key: '0-1',
                num: 0,
                children: [
                    {
                        title: '灌灌灌灌',
                        num: 100,
                        key: '0-1-0-0',
                        checked: true,
                        isLeaf: true
                    },
                    {
                        title: '呜呜呜呜',
                        num: 100,
                        key: '0-2-0-0',
                        checked: false,
                        isLeaf: true
                    },
                ]
            }
        ];
changeTreeData(nodes: any): void {
        nodes.forEach((item: any) => {
            if (item.children) {
                item.children = this.changeTreeData(item.children);
                item.num = 0;
                item.children.forEach((elm: any) => {
                    if (elm.checked && elm.isLeaf) {
                        item.num += elm.num;
                    }
                })
                if (item.num === 0) {
                    item.num = this.changeTotal(item);
                }
            }
        })
        return nodes;
    }

    changeTotal(itemObj: any): any {
        let sum = itemObj.num;
        if (itemObj.children && itemObj.children.length > 0) {
            for (let child of itemObj.children) {
                if (!child.isLeaf) {
                    sum += child.num;
                }
            }
        }
        return sum;
    }
this.changeTreeData(nodes);