/**   * param：o表示检测的值   * return：返回字符串"undefined"、"number"、"boolean"、"string"、"function"、"regexp"、"array"、"date"、"error"、"object"或"null"   */ function typeOf(o){     var _toString = Object.prototype.toString;  //获取对象的toString()方法引用     //列举基本数据类型和内置对象类型，你还可以进一步补充该数组的检测数据类型范围     var _type ={         "undefined" : "undefined",         "number" : "number",         "boolean" : "boolean",         "string" : "string",         "[object Function]" : "function",         "[object RegExp]" : "regexp",         "[object Array]" : "array",         "[object Date]" : "date",         "[object Error]" : "error"     }     return _type[typeof o] || _type[_toString.call(o)] || (o ? "object" : "null"); //通过把值转换为字符串，然后匹配返回字符串中是否包含特定字符进行检测 } //应用示例： var a = Math.abs; alert(typeOf(a));  //返回字符串"function"