(function(){
    // if firefox 3.5+, hide content till load (or 3 seconds) to prevent FOUT
    var d = document,
        e = d.documentElement,
        s = d.createElement('style'),
        r = document.getElementsByTagName('script')[0];
    if (e.style.MozTransform === '') { // gecko 1.9.1 inference
        s.textContent = 'body { visibility: hidden }';
        r.parentNode.insertBefore(s, r);
        function f() {
            s.parentNode && s.parentNode.removeChild(s);
        }
        addEventListener('load', f, false);
        setTimeout(f, 3000);
    }
}) ();

http://paulirish.com/2009/fighting-the-font-face-fout/

FOUT (Flash of Unstyled Text) prevention

JavaScript