Detecting focus of a browser window

Detecting focus of a browser window

function onBlur() {
	document.body.className = 'blurred';
};
function onFocus(){
	document.body.className = 'focused';
};

if (/*@cc_on!@*/false) { // check for Internet Explorer
	document.onfocusin = onFocus;
	document.onfocusout = onBlur;
} else {
	window.onfocus = onFocus;
	window.onblur = onBlur;
}