json 转变成 string方法介绍：
var people = { "programmers": [{ "firstName": "Brett", "lastName": "McLaughlin", "email": "aaaa" }, { "firstName": "Jason", "lastName": "Hunter", "email": "bbbb" }, { "firstName": "Elliotte", "lastName": "Harold", "email": "cccc"}],
"authors": [{ "firstName": "Isaac", "lastName": "Asimov", "genre": "science fiction" }, { "firstName": "Tad", "lastName": "Williams", "genre": "fantasy" }, { "firstName": "Frank", "lastName": "Peretti", "genre": "christian fiction"}],
"musicians": [{ "firstName": "Eric", "lastName": "Clapton", "instrument": "guitar" }, { "firstName": "Sergei", "lastName": "Rachmaninoff", "instrument": "piano"}]
};
alert(JSON.stringify(people));
"authors": [{ "firstName": "Isaac", "lastName": "Asimov", "genre": "science fiction" }, { "firstName": "Tad", "lastName": "Williams", "genre": "fantasy" }, { "firstName": "Frank", "lastName": "Peretti", "genre": "christian fiction"}],
"musicians": [{ "firstName": "Eric", "lastName": "Clapton", "instrument": "guitar" }, { "firstName": "Sergei", "lastName": "Rachmaninoff", "instrument": "piano"}]
};
alert(JSON.stringify(people));
上面的， 只能在IE8或者以上， Firefox下运行
方法toJSONString() ， 必须要引入https://github.com/douglascrockford/JSON-js/blob/master/json.js
局限性都比较大