Change Href Using A Function.

I have a button that change a number of images src's when I click a
button. The src's are stored in an array and I just use
document[imgName1].src=pics[0] to change the src of the image.
However I want the button to change the link as well to the image that
is displayed but i cannot get it to work. How do I do this. Could
someone tell me or point me in the direction of some code that will do
this.

I would like to do it in a similar way to the pictures. i.e. have all
the links stored in an array and change them when the button is
pressed.