problem with JS and Firefox - Image Replacement

Answer 1

The script is fine. This might have something to do with bg class assigned to bg_img image. Probably, the bg has some unsupportable attribute which not work with FF.

EDIT:

To change the background of your page, why don't you just replace the document.bg_img.src with document.body.background.

Answer 2

I'd recommend using a Javascript library like jQuery to help avoid cross-browser issues.

If you want to go ahead without one however, you could try using standard DOM manipulation methods:

document.getElementById('bg_img').setAttribute('src', 'imgs/sandwiches/BLT_smlbw.jpg')

Answer 3

Just use something like this:

function changeBG()
{
    var img = docuemnt.getElementById ("bg_img");
    if( selector == 'portfolio' )
    {
            img.src = 'imgs/sandwiches/BLT_smlbw.jpg';
    }

    else if( selector == 'contact' )
    {
            img.src = 'imgs/sandwiches/eggSammerSml.jpg';
    }
    else
    {
            img.src = 'imgs/plums4.jpg';
    }


}