On May 24, 6:45 am, edfialk <edfi@gmail.com> wrote:
> Hello all, I have this web application up at
http://niceguy.wustl.edu/NEISGEI/EmisComp.
> It's for visually comparing emission data.
> So, I added this nice loading animated gif to the maps to show users
> that the image is still downloading (some data can take a couple of
> minutes). I found the script somewhere on the web.
> Unfortunately, it doesn't work in Internet Explorer (surprise...)
> So, I have 3 maps, 3 loading gifs, 3 loading divs. I'm only showing
> the addLoadEvent function for one, but here's the script:
> document.write('<div id="loading1"><img src="load.gif"></div>');
> document.write('<div id="loading2"><img src="load.gif"></div>');
> document.write('<div id="loading3"><img src="load.gif"></div>');
document.write once:
document.write(
'<div id="loading1"><img src="load.gif"></div>' +
'<div id="loading2"><img src="load.gif"></div>' +
'<div id="loading3"><img src="load.gif"></div>'
);
> function addLoadEvent1(func) {
> var oldonload = window.onload;
> if (typeof window.onload != 'function') {
> window.onload = func;
> } else {
> window.onload = function() {
> if (oldonload) {
> oldonload();
> }
> func();
> }
> }
> }
That is an old method, though still quite effective. There are others
that use a mix of attachEvent and addEventListener (search the
archives[1]). A better version of the above is:
function addLoadEvent1(func) {
var oldonload = window.onload;
if (typeof oldonload == 'function') {
window.onload = function(){
oldonload();
func();
}
} else {
window.onload = func;
}
}
There is a minor issue that if used extensively, the closures that are
formed may consume more memory than you realise. However, it may not
use much more than would have been consumed using addEventListener/
attachEvent, just be aware of it.
1. The following link has a good discussion:
<URL:
http://groups.google.com.au/group/comp.lang.javascript/browse_frm/thr...
--
Rob
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