var arr1 = [ "aaa", "bbb", "ccc" ];      $.each(arr1, function(i,val){      alert(i);   alert(val);
});

　var arr2 = [['a', 'aa', 'aaa'], ['b', 'bb', 'bbb'], ['c', 'cc', 'ccc']]      $.each(arr2, function(i, item){      alert(i);   alert(item);      });  

 var arr = [['a', 'aa', 'aaa'], ['b', 'bb', 'bbb'], ['c', 'cc', 'ccc']]      $.each(arr, function(i, item){      $.each(item,function(j,val){alert(j);alert(val);});
});    

　var obj = { one:1, two:2, three:3}; each(obj, function(key, val) { alert(key); alert(val); });

<input name="aaa" type="hidden" value="111" />
<input name="bbb" type="hidden" value="222" />
<input name="ccc" type="hidden" value="333" />
<input name="ddd" type="hidden"  value="444"/>

 $.each($("input:hidden"), function(i,val){  alert(val);alert(i);alert(val.name);alert(val.value);   }); 

$("input:hidden").each(function(i,val){alert(i);alert(val.name);alert(val.value);
});

function (object, callback, args) {//该方法有三个参数:进行操作的对象obj，进行操作的函数fn，函数的参数argsvar name, i = 0,length = object.length;if (args) {if (length == undefined) {for (name in object) {if (callback.apply(object[name], args) === false) {break;}}} else {for (; i < length;) {if (callback.apply(object[i++], args) === false) {break;}}}} else {if (length == undefined) {for (name in object) {if (callback.call(object[name], name, object[name]) === false) {break;}}} else {for (var value = object[0]; i < length && callback.call(value, i, value) !== false; value = object[++i]) {}/*object[0]取得jQuery对象中的第一个DOM元素，通过for循环，得到遍历整个jQuery对象中对应的每个DOM元素，通过 callback.call( value,i,value);将callback的this对象指向value对象，并且传递两个参数,i表示索引值，value表示DOM元素；其中callback是类似于 function(index, elem) { ... } 的方法。所以就得到 $("...").each(function(index, elem){ ... });*/}}return object;
}