【JavaScript】Object.prototype.toString.call()进行类型判断

权声明：本文为博主原创文章，未经博主允许不得转载。

1. op = Object.prototype,
2. ostring = op.toString,
3. ...
4. function isFunction(it) {
5. return ostring.call(it) === '[object Function]';
6. }
7. function isArray(it) {
8. return ostring.call(it) === '[object Array]';
9. }

最近在看requireJS的源码时，看到上面一段代码，很是好奇，为啥进行类型判断时使用Object.prototype.toString? 如果是我的话就直接用typeof得了，后来查阅了一些资料：

typeof

1. 在使用 typeof 运算符时采用引用类型存储值会出现一个问题，无论引用的是什么类型的对象，它都返回 "object"。

ECMA 对Object.prototype.toString的解释

1. Object.prototype.toString ( )
2. When the toString method is called, the following steps are taken:
3. If the this value is undefined, return "[object Undefined]".
4. If the this value is null, return "[object Null]".
5. Let O be the result of calling ToObject passing the this value as the argument.
6. Let class be the value of the [[Class]] internal property of O.
7. Return the String value that is the result of concatenating the three Strings "[object ", class, and "]".

http://www.ecma-international.org/ecma-262/5.1/#sec-15.2.4.2

1. var oP = Object.prototype,
2. toString = oP.toString;
3. console.log(toString.call([123]));//[object Array]
4. console.log(toString.call('123'));//[object String]
5. console.log(toString.call({a: '123'}));//[object Object]
6. console.log(toString.call(/123/));//[object RegExp]
7. console.log(toString.call(123));//[object Number]
8. console.log(toString.call(undefined));//[object Undefined]
9. console.log(toString.call(null));//[object Null]
10. //....

 // 对Date的扩展，将 Date 转化为指定格式的String
 // 月(M)、日(d)、小时(H)、分(m)、秒(s)、季度(q) 可以用 1-2 个占位符，
 // 年(y)可以用 1-4 个占位符，毫秒(S)只能用 1 个占位符(是 1-3 位的数字)
 // 例子：
 // (new Date()).Format("yyyy-MM-dd hh:mm:ss.S") ==> 2006-07-02 08:09:04.423
 // (new Date()).Format("yyyy-M-d h:m:s.S")      ==> 2006-7-2 8:9:4.18
 Date.prototype.Format = function (fmt) {
     var o = {
         "M+": this.getMonth() + 1, //月份
         "d+": this.getDate(), //日
         "H+": this.getHours(), //小时 --------*********仅支持24小时制**************
         "m+": this.getMinutes(), //分
         "s+": this.getSeconds(), //秒
         "q+": Math.floor((this.getMonth() + 3) / 3), //季度
         "S": this.getMilliseconds() //毫秒
     };
     if (/(y+)/.test(fmt)) fmt = fmt.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length));
     for (var k in o)
         if (new RegExp("(" + k + ")").test(fmt)) fmt = fmt.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
     return fmt;
 };

 //将指定的毫秒数加到此实例的值上
 Date.prototype.addMilliseconds = function (value) {
     var millisecond = this.getMilliseconds();
     this.setMilliseconds(millisecond + value);
     return this;
 };
 //将指定的秒数加到此实例的值上
 Date.prototype.addSeconds = function (value) {
     var second = this.getSeconds();
     this.setSeconds(second + value);
     return this;
 };
 //将指定的分钟数加到此实例的值上
 Date.prototype.addMinutes = function (value) {
     var minute = this.addMinutes();
     this.setMinutes(minute + value);
     return this;
 };
 //将指定的小时数加到此实例的值上
 Date.prototype.addHours = function (value) {
     var hour = this.getHours();
     this.setHours(hour + value);
     return this;
 };
 //将指定的天数加到此实例的值上
 Date.prototype.addDays = function (value) {
     var date = this.getDate();
     this.setDate(date + value);
     return this;
 };
 //将指定的星期数加到此实例的值上
 Date.prototype.addWeeks = function (value) {
     return this.addDays(value * 7);
 };
 //将指定的月份数加到此实例的值上
 Date.prototype.addMonths = function (value) {
     var month = this.getMonth();
     this.setMonth(month + value);
     return this;
 };
 //将指定的年份数加到此实例的值上
 Date.prototype.addYears = function (value) {
     var year = this.getFullYear();
     this.setFullYear(year + value);
     return this;
 };

 /**
  * @ngdoc function
  * @name sUndefined
  * @module ng
  * @kind function
  *
  * @description
  * Determines if a reference is undefined.
  *
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is undefined.
  */
 function isUndefined(value) { return typeof value === 'undefined'; }

 /**
  * @ngdoc function
  * @name sDefined
  * @module ng
  * @kind function
  *
  * @description
  * Determines if a reference is defined.
  *
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is defined.
  */
 function isDefined(value) { return typeof value !== 'undefined'; }

 /**
  * @ngdoc function
  * @name sObject
  * @module ng
  * @kind function
  *
  * @description
  * Determines if a reference is an `Object`. Unlike `typeof` in JavaScript, `null`s are not
  * considered to be objects. Note that JavaScript arrays are objects.
  *
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is an `Object` but not `null`.
  */
 function isObject(value) {
     // http://jsperf.com/isobject4
     return value !== null && typeof value === 'object';
 }

 /**
  * Determine if a value is an object with a null prototype
  *
  * @returns {boolean} True if `value` is an `Object` with a null prototype
  */
 function isBlankObject(value) {
     return value !== null && typeof value === 'object' && !getPrototypeOf(value);
 }

 /**
  * @ngdoc function
  * @name sString
  * @module ng
  * @kind function
  *
  * @description
  * Determines if a reference is a `String`.
  *
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is a `String`.
  */
 function isString(value) { return typeof value === 'string'; }

 /**
  * @ngdoc function
  * @name sNumber
  * @module ng
  * @kind function
  *
  * @description
  * Determines if a reference is a `Number`.
  *
  * This includes the "special" numbers `NaN`, `+Infinity` and `-Infinity`.
  *
  * If you wish to exclude these then you can use the native
  * [`isFinite'](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isFinite)
  * method.
  *
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is a `Number`.
  */
 function isNumber(value) { return typeof value === 'number'; }

 /**
  * @ngdoc function
  * @name sDate
  * @module ng
  * @kind function
  *
  * @description
  * Determines if a value is a date.
  *
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is a `Date`.
  */
 function isDate(value) {
     return Object.prototype.toString.call(value) === '[object Date]';
 }

 /**
  * @ngdoc function
  * @name sArray
  * @module ng
  * @kind function
  *
  * @description
  * Determines if a reference is an `Array`.
  *
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is an `Array`.
  */

 function isArray(value) {
     return Object.prototype.toString.call(value) === '[object Array]';
 }

 /**
  * @ngdoc function
  * @name sFunction
  * @module ng
  * @kind function
  *
  * @description
  * Determines if a reference is a `Function`.
  *
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is a `Function`.
  */
 function isFunction(value) { return typeof value === 'function'; }

 /**
  * Determines if a value is a regular expression object.
  *
  * @private
  * @param {*} value Reference to check.
  * @returns {boolean} True if `value` is a `RegExp`.
  */
 function isRegExp(value) {
     return Object.prototype.toString.call(value) === '[object RegExp]';
 }

 /**
  * Checks if `obj` is a window object.
  *
  * @private
  * @param {*} obj Object to check
  * @returns {boolean} True if `obj` is a window obj.
  */
 function isWindow(obj) {
     return obj && obj.window === obj;
 }

 function isScope(obj) {
     return obj && obj.$evalAsync && obj.$watch;
 }

 function isFile(obj) {
     return Object.prototype.toString.call(obj) === '[object File]';
 }

 function isFormData(obj) {
     return Object.prototype.toString.call(obj) === '[object FormData]';
 }

 function isBlob(obj) {
     return Object.prototype.toString.call(obj) === '[object Blob]';
 }

 function isBoolean(value) {
     return typeof value === 'boolean';
 }

 function isNullOrEmpty(str) {
     if (str && str.length > 0) {
         return false;
     }
     return true;
 }

 function trim(str)
 {
     return str.replace(/(^\s*)|(\s*$)/g, '');
 }     

 function ltrim(str)
 {
     return str.replace(/^\s*/g,'');
 }     

 function rtrim(str)
 {
     return str.replace(/\s*$/,'');
 }     

 function equals(str1, str2)
 {
     if(str1 == str2)
     {
         return true;
     }
     return false;
 }     

 function equalsIgnoreCase(str1, str2)
 {
     if(str1.toUpperCase() == str2.toUpperCase())
     {
         return true;
     }
     return false;
 }     

 function isChinese(str)
 {
     var str = str.replace(/(^\s*)|(\s*$)/g,'');
     if (!(/^[\u4E00-\uFA29]*$/.test(str)
             && (!/^[\uE7C7-\uE7F3]*$/.test(str))))
     {
         return false;
     }
     return true;
 }     

 function isEmail(str)
 {
     if(/^[\w-]+(\.[\w-]+)*@[\w-]+(\.[\w-]+)+$/.test(str))
     {
         return true
     }
     return false;
 }     

 function isImg(str)
 {
     var objReg = new RegExp("[.]+(jpg|jpeg|swf|gif)$", "gi");
     if(objReg.test(str))
     {
         return true;
     }
     return false;
 }     

 function isInteger(str)
 {
     if(/^-?\d+$/.test(str))
     {
         return true;
     }
     return false;
 }     

 function isFloat(str)
 {
     if(/^(-?\d+)(\.\d+)?$/.test(str))
     {
         return true;
     }
     return false;
 }     

 function isMobile(str)
 {
     if(/^1[35]\d{9}/.test(str))
     {
         return true;
     }
     return false;
 }     

 function isPhone(str)
 {
     if(/^(0[1-9]\d{1,2}-)\d{7,8}(-\d{1,8})?/.test(str))
     {
         return true;
     }
     return false;
 }     

 function isIP(str){
     var reg = /^(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])$/;
     if(reg.test(str))
     {
         return true;
     }
     return false;
 }     

 function isDateTimeString(str)
 {
     var reg = /^((((1[6-9]|[2-9]\d)\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})-0?2-(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$/;
     if(reg.test(str))
     {
         return true;
     }
     return false;
 }