关于Jquery中的$.each获取各种返回类型数据的使用方法

var arr = [ "one", "two", "three", "four"];     
 $.each(arr, function(){     
    alert(this);     
 });  

var arr = [ "aaa", "bbb", "ccc" ];      
$.each(arr, function(i,a){      
  alert(i);   // i 是循环的序数
  alert(a);  // a 是值
}); 

var arr1 = [[1, 4, 3], [4, 6, 6], [7, 20, 9]]     
$.each(arr1, function(i, item){     
   alert(item[0]);     
});  

var obj = { one:1, two:2, three:3, four:4};     
$.each(obj, function(key, val) {     
    alert(obj[key]);
    alert(key);   //键
    alert(val);    //值

});