Treehouse

Use Custom Missing Image Graphics Using Dojo

By on  

A few months back I posted an article about how you can use your own “missing image” graphics when an image fails to load using MooTools and jQuery. Here’s how to do the same using Dojo.

The HTML

<p><img src="http://cnn.com/image-that-doesnt-exist.jpg" alt="Missing 1" class="missing1" /></p>
<p><img src="http://cnn.com/demo/image-that-doesnt-exist-2.jpg" alt="Missing 2" class="missing2" /></p>

We'll delegate the image to display by class -- be sure to give the appropriate class to each image. We'll be using two images for the sake of this demo.

The Dojo JavaScript

dojo.addOnLoad(function() {
	/* version 1 */
	dojo.query('img.missing1').connect('onerror',function() {
		dojo.attr(this,{
			src: 'http://davidwalsh.name/demo/missing-image.jpg',
			alt: 'Sorry!  This image is not available!',
			style:'border: 1px solid #f00;width:110px;height:40px;'
		});
	});
	/* version 2 */
	dojo.query('img.missing2').connect('onerror',function() {
		dojo.attr(this,{
			src: 'http://davidwalsh.name/demo/missing-image-2.jpg',
			alt: 'Sorry!  This image is not available!',
			style:'border: 1px solid #f00;width:30px;height:28px;'
		});
	});
});

We query the DOM for both classes and replace any broken images (we can tell there ways a problem because the onError event fires) with the two designated images. Simple!

Of course you should always do what you can on the server side to prevent broken images -- the small javascript snippet above should be used as a safeguard.

ydkjs-4.png

Recent Features

  • Facebook Open Graph META&nbsp;Tags

    It's no secret that Facebook has become a major traffic driver for all types of websites.  Nowadays even large corporations steer consumers toward their Facebook pages instead of the corporate websites directly.  And of course there are Facebook "Like" and "Recommend" widgets on every website.  One...

  • Page Visibility&nbsp;API

    One event that's always been lacking within the document is a signal for when the user is looking at a given tab, or another tab. When does the user switch off our site to look at something else? When do they come back?...

Incredible Demos

  • Create Keyboard Shortcuts with&nbsp;Mousetrap

    Some of the finest parts of web apps are hidden in the little things.  These "small details" can often add up to big, big gains.  One of those small gains can be found in keyboard shortcuts.  Awesome web apps like Gmail and GitHub use loads of...

  • Create a CSS&nbsp;Cube

    CSS cubes really showcase what CSS has become over the years, evolving from simple color and dimension directives to a language capable of creating deep, creative visuals.  Add animation and you've got something really neat.  Unfortunately each CSS cube tutorial I've read is a bit...

Discussion

    Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!