1. var getProto = Object.getPrototypeOf; //用来获取当前某一个对象的原型
    2. var class2type = {};
    3. var toString = class2type.toString; //Object.prototype.toString
    4. var hasOwn = class2type.hasOwnProperty; //Object.prototype.hasOwnProperty
    5. var fnToString = hasOwn.toString; //函数.toString=>Function.prototype.toString
    6. var ObjectFunctionString = fnToString.call(Object); //=>Function.prototype.toString 执行，把方法中的this更改为Object [相当于]=>Object.toString()  => "function Object() { [native code] }"
    8. // 检测是否是一个函数
    9. var isFunction = function isFunction(obj) {
    10.     return typeof obj === "function" && typeof obj.nodeType !== "number" &&
    11.         typeof obj.item !== "function";
    12. };
    14. // 检测是否是一个window对象
    15. var isWindow = function isWindow(obj) {
    16.     // window.window===window 实现了套娃操作
    17.     return obj != null && obj === obj.window;
    18. };
    20. // 标准的检测数据类型的办法
    21. /* var arr = ["Boolean", "Number", "String", "Function", "Array", "Date", "RegExp", "Object", "Error", "Symbol"];
    22. arr.forEach(function (name) {
    23.     class2type["[object " + name + "]"] = name.toLowerCase();
    24. });
    25. var toType = function toType(obj) {
    26.     if (obj == null) return obj + "";
    27.     //null和undefined 直接拼接成 字符串
    28.     return typeof obj === "object" || typeof obj === "function" ?
    29.         class2type[toString.call(obj)] || "object" :
    30.         typeof obj;
    31. }; */
    33. //正则优化
    34. var toType = function toType(obj) {
    35.     if (obj == null) return obj + "";
    36.     var reg = /^\[object ([a-zA-Z0-9]+)\]$/i;
    37.     return typeof obj === "object" || typeof obj === "function" ?
    38.         reg.exec(toString.call(obj))[1].toLowerCase() :
    39.         typeof obj;
    40. };
    42. // 检测是否为数组或者类数组
    43. var isArrayLike = function isArrayLike(obj) {
    44.     var length = !!obj && "length" in obj && obj.length,
    45.         type = toType(obj);
    46.     if (isFunction(obj) || isWindow(obj)) return false;
    47.     return type === "array" || length === 0 ||
    48.         typeof length === "number" && length > 0 && (length - 1) in obj;
    49. };
    51. // 检测是否为纯粹的对象「直属类是Object || Object.create(null)」
    52. var isPlainObject = function isPlainObject(obj) {
    53.     var proto, Ctor;
    54.     if (!obj || toString.call(obj) !== "[object Object]") return false;
    55.     proto = getProto(obj);
    56.     if (!proto) return true;
    57.     Ctor = hasOwn.call(proto, "constructor") && proto.constructor;
    58.     return typeof Ctor === "function" && fnToString.call(Ctor) === ObjectFunctionString;
    59. };
    61. // 检测是否是空对象
    62. var isEmptyObject = function isEmptyObject(obj) {
    63.     var keys = Object.keys(obj);
    64.     if (typeof Symbol !== "undefined") keys = keys.concat(Object.getOwnPropertySymbols(obj));
    65.     return keys.length === 0;
    66. };
    68. // 检测是否是数字
    69. var isNumeric = function isNumeric(obj) {
    70.     var type = toType(obj);
    71.     return (type === "number" || type === "string") && !isNaN(obj);
    72. };