var str = '{"name":"cxh","sex":"man","age":"25"}'; 

//方法一：eval方式解析

var obj1 = eval('(' + str + ')');

console.log(obj1.name);

//方法二：使用全局的JSON对象解析，使用JSON.parse需严格遵守JSON规范，如属性都需用引号引起来

var obj2 = JSON.parse(str);

console.log(obj2.sex);

//方法三：new Function形式解析

var obj3 = (new Function("return" + str))();

console.log(obj3.age);

 var obj = {"name":"cxh","sex":"man","age":"25"};

 var str = JSON.stringify(obj);

 console.log(str);