title: Changing image src on button click
body: <p>I have a <em>holding page</em> for a site Under Construction.</p>
  
  <p>There is an image and a box with a button. on clicking the button I want the image to change.</p>
  
  <p>There will be collections of images with the same name plus a subscript 
  (eg:  TG-img-<strong>01</strong>.jpg).<br>
  Idea is to increment the subscript.  </p>
  
  <p>Not used JavaScript for 15 years,  so looking for examples of how it can be done. </p>
  
  <p>cheers.</p>