javascript sleep function

sleep.js

// WARNINGS:: This function is *relatively* untested (i.e. there is no formal testing as of yet).  Use at your own risk.
//            It is normally MUCH better to use setTimeout or requestAnimationFrame than to block in a single-threaded environment, be KIND to your users
//            This function is best suited to testing the behaviour of an application when intensive processing occurs

function sleep(ms){
    var initial = +new Date()           
    while(+new Date() < initial + ms){}
}