SOURCE

const arr = [
    {
        title: '手机',
        key: '0',
        children: [
            { title: '苹果', key: '0-0' },
            { title: '小米', key: '0-1', children: [{ title: '12s', key: '0-1-0' }] },
        ],
    },
    {
        title: '平板',
        key: '1',
        children: [
            { title: '华为', key: '1-0' },
            { title: '联想', key: '1-1', children: [{ title: 's8', key: '1-1-0' }] },
        ],
    },
    {
        title: '耳机',
        key: '2',
        children: [
            {
                title: 'vivo',
                key: '2-0',
            },
        ],
    },
]
let str = ''
const indexs = [0, 1, 0];
indexs.forEach((key, i) => {
    if (i == 0) {
        cur = arr[indexs[i]]
    } else {
        cur = cur['children'][indexs[i]]
    }
    str += (cur.title);
})
console.log(str)