[javascript] How to convert JSON to string?

You can use the JSON stringify method.

JSON.stringify({x: 5, y: 6}); // '{"x":5,"y":6}' or '{"y":6,"x":5}'

There is pretty good support for this across the board when it comes to browsers, as shown on http://caniuse.com/#search=JSON. You will note, however, that versions of IE earlier than 8 do not support this functionality natively.

If you wish to cater to those users as well you will need a shim. Douglas Crockford has provided his own JSON Parser on github.