json的常用数据格式
{ name:value } Object , 键值对形式的对象
[ Object,Object ] 对象数组
示例：
var o=[{"f1":7},{"f2":4},{"c":[{"id":1,"name":"a1"},{"id":2,"name":"a2",}]},{"d":[{"id":3,"name":"a3"},{"id":4,"name":"a4"}]}];
o[0].f1 == 7
0[1].f2 == 4
o[2].c[0].id == 1
o[2].c[0].name == "a1"
o[3].d[1].id == 4
o[3].d[1].name == "a4"