Math.randomMax = function(maxVal,asFloat){ var val = Math.random()*maxVal; return asFloat?val:Math.round(val); } function rotateAds(){ var adArray = new Array(); adArray[0] = new Array(); adArray[0][0] = "http://prm.virgul.com/ad_view1215.php"; adArray[0][1] = "100"; var random = Math.randomMax(100); var offset = 0; var count = adArray.length; for (i = 0; i < count; i++) { offset += adArray[i][1]; if (random <= offset) { document.write(''); return; } } } rotateAds();