IFrames - Change SRC To Display New Page

I have an Iframe and some links to different pages. I have the code set up so that it changes the "src" to display the new page. The reason I have it set this was is because I want to be able to manipulate the content in the Iframe. I want to be able to hidden a portion of the new page once it is rendered in the iframe. This is what i have so far. Basically I need my intoIframe function to execute only after the has fully executed. How I accomplish this

Code:
function completeView(){
var tds = document.getElementById("alinks");
var link = tds.getElementsByTagName("a");
for ( i=0; i<link.length - 1; i++){
if ( i > 0){
link[i].onclick = function(){
showDoc(this);
return false;
}}}}
addLoadEvent(completeView);

function showDoc(whichDoc){
if (!document.getElementById || !document.getElementsByTagName || !document.getElementById("viewer"))return false;
var source = whichDoc.getAttribute("href");
var placeholder = document.getElementById("viewer");
placeholder.setAttribute("src",source);
}

function intoIframeUP(){
if (window.frames[0] != null){ alert('Frame is here');}
var mine = window.frames[0].document.getElementsByTagName("body")[0].innerHTML;
var sharepoint = window.frames[0].document.body.innerHTML;
alert(sharepoint);
}