JavaScript Step by Step, Second Edition by Steve Suehring

Author:Steve Suehring [Steve Suehring]
Language: eng
Format: epub
Tags: COMPUTERS / Programming Languages / JavaScript
ISBN: 9780735645530
Publisher: Microsoft Press
Published: 2010-12-19T16:00:00+00:00

Next, a script in the body of the document connects the nextImage()function to the click event of the Next button by using the EHandler add() method:

<script type="text/javascript"> var nextBtn = document.getElementById("nextbtn"); EHandler.add(nextBtn,"click",function() { nextImage(); }); </script>

At this point, when a user clicks the Next button, the script will call the nextImage() function. The nextImage() function retrieves the image object from the <img> HTML tag, using the getElementById() function. Next, it splits the name attribute of that image at the underscore character, so the function can obtain the number from the ending characters of the name attribute. It stores that number in the index variable.

The next portion of the code performs a conditional test that checks whether the index value equals the length of the images array minus 1. If this condition is true, the user has reached the end of the slideshow, so the script sets the index value back to 0 to start over. If the slide-show has not yet reached the end of the available images, the code increments the index value by 1.

The final two lines of JavaScript set the src attribute to the new image and set its name appropriately so that the next time the code goes through the function, the current index can be determined.

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