Question

I’m trying to do a popup via JavaScript to popup the IMG URL which is what the img tag is defining through src=

I’m not sure how to call it.

alert(document.getElementById("my_image").src);

Answer 1

It’s better to use the getAttribute() function:

var imageSource = document.getElementById("my_image").getAttribute('src');
alert(imageSource);

Using getAttribute() is more suitable for your application than simply using element.src, since it will return the explicit defined value inside the attribute, rather than the parsed value.

See the comparison here > http://jsfiddle.net/9dAjL/