Question

I am trying to get the last date that a remote url was updated using javascript. I have currently come up with this:

function getlastmod(url)
{
    var ifrm = document.createElement("IFRAME"); 
    ifrm.setAttribute("src", url);
    ifrm.setAttribute("id", "oIFRAME");
    ifrm.style.display = "none"; 
    var spanTag = document.createElement("span"); 
    spanTag.id = "oSpan"; 
    try 
    {
        var oIFrame = document.getElementById("oIFrame");
        var oSpan = document.getElementById("oSpan");
        oSpan.innerHTML = oIFrame.src + " last modified " +
        oIFrame.document.lastModified;
        outUpdate=oSpan;
    } 
    catch(E) {setTimeout("getlastmod();",50);}
}

However, this code seems to always change ‘outUpdate’ to “undefined”. The code is supposed to load the url contents into a frame and then use the document.lastModified function to get the last modified date.

Any ideas on how to fix this?

Thanks!
Josh

Answer 1

You are accessing the element oIFRAME & oSpan before adding them to your document, you have to add these 2 lines before the try block:

document.body.appendChild(ifrm);
document.body.appendChild(spanTag);

The id of your iFrame is oIFRAME and not oIFrame, replace this line:

var oIFrame = document.getElementById("oIFrame");

By

var oIFrame = document.getElementById("oIFRAME");

document is not a property of your iFrame object, contentDocument is. Replace this line

oIFrame.document.lastModified;

by

oIFrame.contentDocument.lastModified;