JS 检测是否为纯粹的对象

 let class2type = {},
        toString = class2type.toString,
        hasOwn = class2type.hasOwnProperty,
        fnToString = hasOwn.toString,
        ObjectFunctionString = fnToString.call(Object),
        getProto = Object.getPrototypeOf; 
const isPlainObject = function isPlainObject(obj) {
        let proto, Ctor;
        if (!obj || toString.call(obj) !== "[object Object]") return false;
        proto = getProto(obj);
        if (!proto) return true;
        Ctor = hasOwn.call(proto, "constructor") && proto.constructor;
        return typeof Ctor === "function" && fnToString.call(Ctor) === ObjectFunctionString;
    };