var span=document.getElementsByTagName('span')[0];
var div=document.getElementsByTagName('div')[0];
var strong=document.createElement('strong');
var em=document.getElementsByTagName('em')[0];
Element.prototype.insertAfter=function(target,afternode){
if(afternode.nextElementSibling){
var node=afternode.nextElementSibling;
this.insertBefore(target,node);
}else{
this.appendChild(target);
}
}