jquery怎样判断是否是字符串

var str="ss";

alert((typeof str=='string')&&str.constructor==String)

var obj=[0];

alert((typeof obj=='object')&&obj.constructor==Array)

function isString(obj){ //判断对象是否是字符串 

   return Object.prototype.toString.call(obj) === "[object String]"; 

} 

验证：

var str1 = 'abc';

var str2 = new String('abc');

typeof str1; //"string"

typeof str2; //"object"

Object.prototype.toString.call(str1); //"[object String]"

Object.prototype.toString.call(str2); //"[object String]"

var str=547.97;

alert((typeof str=='number')&&str.constructor==Number)

var obj =new Date();

alert((typeof obj=='object')&&obj.constructor==Date)

var obj = function test(){};

alert((typeof obj=='function')&&obj.constructor==Function)