js遍历树形结构并返回所有的子节点id值

var treeData = [{
        id: 111,
        title: "机构1",
        children: [{
                id: 123,
                title: "机构1",
            },
            {
                id: 11123,
                title: "机构1231",
                children: [{
                    id: 111211231233,
                    title: "机构1231",
                }]
            },
            {
                id: 11121212123,
                title: "机构11111231",
            }
        ]
    },
    {
        id: 1112111113,
        title: "机构1211131",
        children: [{
            id: 1110000211231233,
            title: "机构12300001",
        }]
    },
    {
        id: 110001112113,
        title: "机构1211000111211331",
        children: [{
            id: 11100999911231233,
            title: "机构100002300001",
            children: [{
                id: 100,
                title: "机构l",
            }]
        }]
    },
    {
        id: 9999,
        title: "部门11",
        children: [{
            id: 000233,
            title: "部门31",
            children: [{
                id: 110,
                title: "机2构l",
            }]
        }]
    },
]

function lookForAllId(data = [], arr = []) {
    for (let item of data) {
        arr.push(item.id)
        if (item.children && item.children.length) lookForAllId(item.children, arr)
    }
    return arr
}
console.log(lookForAllId(treeData));