一.  JSON对象和JSON字符串之间的转换

1. json字符串----->json对象

   • 使用JSON.parse()函数

     var jsonStr = '{"name":"zhangsan","age":23,"email":"chentging@aliyun.com"}';
     var json = JSON.parse(jsonStr);
     console.log(json);//输出:Object {name: "zhangsan", age: 23, email: "chentging@aliyun.com"}

   • 使用eval()函数

     var jsonStr = '{"name":"zhangsan","age":23,"email":"chentging@aliyun.com"}';
     var json = eval ("(" + jsonStr + ")");
     console.log(json);//输出:Object {name: "zhangsan", age: 23, email: "chentging@aliyun.com"}

   • 使用jQuery插件jQuery.parseJSON()

     var jsonStr = '{"name":"zhangsan","age":23,"email":"chentging@aliyun.com"}';
     var json = jQuery.parseJSON(jsonStr);
     console.log(json);//输出:Object {name: "zhangsan", age: 23, email: "chentging@aliyun.com"}

2. json对象------>json字符串

• 使用JSON.stringify()

  var json = {name: "zhangsan", age: 23, email: "chentging@aliyun.com"};
  var jsonStr = JSON.stringify(json);
  console.log(jsonStr);//输出:"{"name":"zhangsan","age":23,"email":"chentging@aliyun.com"}"

把数据在前后端之间传递，需要把json对象转换为json字符串