如果这是你的数据数组:

var dataArray = [{"id":28,"class":"Sweden"}, {"id":56,"class":"USA"}, {"id":89,"class":"England"}];

然后:

$(jQuery.parseJSON(JSON.stringify(dataArray))).each(function() {  
         var ID = this.id;
         var CLASS = this.class;
});

取自jQuery文档:

var arr = [ "one", "two", "three", "four", "five" ];
var obj = { one:1, two:2, three:3, four:4, five:5 };

jQuery.each(arr, function() {
  $("#" + this).text("My id is " + this + ".");
  return (this != "four"); // will stop running to skip "five"
});

jQuery.each(obj, function(i, val) {
  $("#" + i).append(document.createTextNode(" - " + val));
});

mootools的例子:

var ret = JSON.decode(jsonstr);

ret.each(function(item){
    alert(item.id+'_'+item.classd);
});

如果不容易，请告诉我:

var jsonObject = {
  name: 'Amit Kumar',
  Age: '27'
};

for (var prop in jsonObject) {
  alert("Key:" + prop);
  alert("Value:" + jsonObject[prop]);
}

你可以使用像objx - http://objx.googlecode.com/这样的迷你库

你可以这样写代码:

var data =  [ {"id":"10", "class": "child-of-9"},
              {"id":"11", "class": "child-of-10"}];

// alert all IDs
objx(data).each(function(item) { alert(item.id) });

// get all IDs into a new array
var ids = objx(data).collect("id").obj();

// group by class
var grouped = objx(data).group(function(item){ return item.class; }).obj()

还有更多的“插件”可以让你这样处理数据，请参阅http://code.google.com/p/objx-plugins/wiki/PluginLibrary

从http://www.w3schools.com复制和粘贴，不需要JQuery开销。

var person = {fname:"John", lname:"Doe", age:25};

var text = "";
var x;
for (x in person) {
    text += person[x];
}

结果:无名氏25人