JavaScript 判断一个对象的数据类型。

1、isString

var isString1 = function (obj){
   return Object.prototype.toString.call(obj)==="[object String]";
};


var isString2 = function(obj){
    return (typeof obj==="string")
};


var isString3 = function (obj) {
    return ("" + obj) === obj;
};

2、isArray

var isArray1 = function(obj){
    return Object.prototype.toString.call(obj)==="[object Array]"
};

var isArray2 = function(obj){
    return obj instanceof Array;
};

var isArray3 = function(obj){
    return Array.isArray(obj); //需要浏览器支持
};

3、其他

 var toString = Object.prototype.toString;


   //判读一个对象是一个对象
  _.isObject = function(obj) {
    var type = typeof obj;
    return type === 'function' || type === 'object' && !!obj;
  };


  // isArguments, isFunction, isString, isNumber, isDate, isRegExp, isError.
  _.each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp', 'Error'], function(name) {
    _['is' + name] = function(obj) {
      return toString.call(obj) === '[object ' + name + ']';
    };
  });