function firdom(){
if(document.getElementsByTagName && document.createElement){
var h1s=document.getElementsByTagName('a');
scanandreplace(h1s,'a');
}

}
function scanandreplace(h1s,tag){
for(var i=0;i<h1s.length;i++){
for(var f=0;f<replaceImages.length;f++){
var chunks=replaceImages[f].split('|');
var thish1=document.getElementsByTagName(tag)[i];
if(thish1.firstChild.nodeValue==chunks[0]){
var newImg=document.createElement('img');
newImg.setAttribute('alt',chunks[0])
newImg.setAttribute('src',chunks[1])
// or newImg.src=chunks[1];
thish1.replaceChild(newImg,thish1.firstChild)
break;
}
}
}
}
window.onload=firdom;