You can use setTimeout to "free up the event loop". Using setTimeout(fun, 0) will run fun after the event loop has been freed up IIRC. NodeJS has a function called setImmediate that does exactly that.

JSON.parse as implemented is going to be blocking. But it's possible to implement an asynchronous, non-blocking JSON parser

See also : http://stackoverflow.com/questions/779379/why-is-settimeoutf...

Edit : requestAnimationFrame is a better alternative to setTimeout(fun, 0), as it allows the browser to update the UI.