var count=1; //initialise the image counter to 1 function nextPic() { // Define a function to move to next image if (count < 26) { // There will be 26 images count ++ // Add 1 to the counter document.display.src=count+".jpg"; //Show the image called 1.jpg } else { count=1 // when the counter is 26 go back to 1 document.display.src="1.jpg"; } } function prevPic() { // Define a function to get the previous image if (count >1) { count -- // Subtract 1 from the counter document.display.src=count+".jpg"; } else { count=26 // When the counter is 1 go to 26 document.display.src="26.jpg"; } }