JS 标准检测数据类型的方法

  // 标准的检测数据类型的办法
 let class2type = {},
      toString = class2type.toString,
    const toType = function toType(obj) {
        if (obj == null) return obj + "";
        let reg = /^\[object ([a-zA-Z0-9]+)\]$/i;
        return typeof obj === "object" || typeof obj === "function" ?
            reg.exec(toString.call(obj))[1].toLowerCase() :
            typeof obj;
    };