json转成string[需要引用json2.js文件]：
var arr=[{id:'id',name:'Spring'},{id:'id2',name:'Jane'}];
var str=JSON.stringify(arr);
结果："[{id:'id',name:'Spring'},{id:'id2',name:'Jane'}]"
string转化为json:
var str="[{id:'id',name:'Spring'},{id:'id2',name:'Jane'}]";
var json=$.parseJSON(str);
结果：[{id:'id',name:'Spring'},{id:'id2',name:'Jane'}]