Javascript String addToElement(tag, className)

String.prototype.addToElement = function(tag, className)
{
 this.tagName = 'tag';
 this.className = 'className';
 return '<'+tag+' class='+className+'>' + this + '</'+tag+'>';
}

window.onload = function()
{
 var str = document.getElementsByTagName('p');
 str.addToElement("DIV", 'red');
}