如何设置对象属性（..的对象属性）在JavaScript中给定其字符串名称？

function assign(obj, prop, value) {    if (typeof prop === "string")        prop = prop.split(".");    if (prop.length > 1) {        var e = prop.shift();        assign(obj[e] =      Object.prototype.toString.call(obj[e]) === "[object Object]"      ? obj[e]      : {},    prop,    value);    } else        obj[prop[0]] = value;}var obj = {},    propName = "foo.bar.foobar";assign(obj, propName, "Value");