Java script useful function

[Homer_simpson]

I got this function from a tutorial it seems pretty useful so i post it here:

code:

function checkIfInstalled(fname){    loaded = document.readyState == "complete";    teststr = "font&nbsp;existence&nbsp;test"    if(!window.fntLyr0) {       lyrstr0 = "<SPAN ID=fntLyr0 STYLE='position:absolute;width:30;font:12pt Courier'>"+ teststr +"</SPAN>";       lyrstr1 = "<SPAN ID=fntLyr1 STYLE='position:absolute;width:30;font-size:12pt'>"+ teststr +"</SPAN>";       if (loaded) {          document.body.insertAdjacentHTML("BeforeEnd",lyrstr0);               document.body.insertAdjacentHTML("BeforeEnd",lyrstr1);       }       else {          document.write(lyrstr0);          document.write(lyrstr1);       }    }    fntLyr1.style.fontFamily = fname +",Courier";    width0 = (isMac) ? fntLyr0.offsetWidth : fntLyr0.scrollWidth;    width1 = (isMac) ? fntLyr1.offsetWidth : fntLyr1.scrollWidth;    return (width0 != width1); }

fname is the font name that yer checking to see if installed... then function reutrns a boolean to show whether it's installed or not...