学步园

1.each(callback):替代了for..in

$(document).ready(function(){
/*	var attr=[11,22,33];
	$(attr).each(function(index,item){
		alert(item);
	});
	var attr=[11,22,33];
	$.each(attr,function(index,item){//和上面一样
		alert(item);
	});
	*/
	$("div").each(function(index,item){
		if(index==1){
			$(this).text("aaaa");
		}
	});
});

$(document).ready(function(){
	var json=[{"name":"aa","age":18},{"name":"ab","age":19}];
	$(json).each(function(index,item){
		alert(item.name)
	});
});

2.map(callback):必须要有return,否则为null,每次使用map都是一个新的集合,而each不是

$(document).ready(function(){
	var attr=[11,22,33];
	var attr1=$(attr).map(function(index,item){
		return item*10;
	});
	alert(attr+" "+attr1[1])
});