jQuery源码-数据类型检测

(function () {
     
    "use strict";
    var class2type = {
     };
    var getProto = Object.getPrototypeOf;
    var toString = class2type.toString; //->Object.prototype.toString
    var hasOwn = class2type.hasOwnProperty; //->Object.prototype.hasOwnProperty
    var fnToString = hasOwn.toString; //->Function.prototype.toString
    var ObjectFunctionString = fnToString.call(Object); //->Object.toString()  //->"function Object() { [native code] }"

    // 建立数据类型检测的映射表
    var arr_type = ["Boolean", "Number", "String", "Function", "Array", "Date", "RegExp", "Object", "Error", "Symbol", "BigInt"];
    arr_type.forEach(function (name) {
     
        class2type["[object " + name + "]"] = name.toLowerCase();
    });
    
    // 通用检测方法
    var toType = function toType(obj) {
     
        //null/undefined
        if (obj == null) return obj + "";
        return typeof obj === "object" || typeof obj === "function" ?
            class2type[toString.call(obj)] || "object" :
            typeof obj;
    };

    // 检测是否为函数
    var isFunction = function isFunction(obj) {
     
        // In some browsers, typeof returns "function" for HTML