封装个方法利用eval字符串运行直接开撸...

var obj = {}

function change(json, ary, val) {
    ary.forEach((e, i) => {
        const objStr = `json.${ary.slice(0,i+1).join('.')}`
        const isExist = eval(objStr)
        if (isExist === undefined) eval(`${objStr} = {}`)
        if (i === ary.length - 1) eval(`${objStr} = ${typeof val === 'string'?`'${val}'`:val}`)
    })
}

change(obj, ['a', 'b', 'c', 'd'], '赋上了新的值')