jQuery Stop Action Improves InnerFade Plugin

Posted on 17 January 2012 by axe

When animations go wrong it’s usually in the timing. Perhaps the browser can’t keep up with all that it’s asked to do or the operating system is bogged down by other tasks. In any case the lack of enough working memory or CPU cycles will have animations stacking up until there are enough resources to do all those fancy moves.

Some animations run continuously and others may be controlled by setting timers or stopping the animations at predetermined times. Other animations happen after some event has occurred, like when a user mouses over an element on the page or clicks a button.

Animations created with the jQuery InnerFade plugin run continuously, which may create a problem if the users’ computer resources aren’t up to the job.

It was noted that an InnerFade news ticker animation of links worked fine and as expected when the browser tab was left open and running. Working with another tab open and going back to the news ticker site, the news items got stacked onto one another so that the text was unreadable and the timing was double time.

Reloading the page or waiting for a couple of seconds to pass brought the expected behavior back. The animations caught up to where they should have been and the behavior continued as expected.

I’m not exactly sure why the animations stacked up in my page and not in the demo page by the plugin author, but I found a solution to this stacking problem.

jQuery lets us use a stop() action to clear the previously requested animations that haven’t finished yet. Optional parameters for the stop() action are clearQueue and gotoEnd, which are false by default.

To use the stop() action in this case, set both parameters to true. This will clear all animations in the queue and jump to the place where the action should be at now.

If it were important to catch up to the latest animation, use true for the optional gotoEnd parameter. When set to true, the gotoEnd parameter figures out what the screen should look like at the end of the present set of animations in the queue and goes there.

In the section of the code that responds to the slide or fade settings, I used the stop() action to clear the queue and catch up. The InnerFade plugin was altered on lines 93 and 96 (of the original script) by inserting .stop(true,true) just before the fadeOut() or slideUp() methods.

line 93...$(elements[last]).stop(true,true).slideUp(settings.speed);
line 96...$(elements[last]).stop(true,true).fadeOut(settings.speed);

Below is the portion of the original script that has been modified (on lines 3 and 6 here):

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$.innerfade.next = function(elements, settings, current, last) {
if (settings.animationtype == 'slide') {
$(elements[last]).stop(true,true).slideUp(settings.speed);
$(elements[current]).slideDown(settings.speed);
} else if (settings.animationtype == 'fade') {
$(elements[last]).stop(true,true).fadeOut(settings.speed);
$(elements[current]).fadeIn(settings.speed, function() {
                            removeFilter($(this)[0]);
                        });

The script now works even better!

When two separate link lists were animated with the InnerFade plugin on the same page, the first one stacked up and the second list went blank when the stop() action was used with only the first parameter set to true, so it was important to set both the clearQueue and gotoEnd parameters to true.

The stop() action also comes in handy to clear the queue when event-driven animations get backed up from too much user input, like mousing over and out too fast.

An oddity in all this is that I couldn’t replicate the bad behavior (of the original plugin) inside of WordPress. The stacking up of animations was noticed in a static page outside of WordPress. To see the original and improved InnerFade plugins in action, go to the Good Ideas static page.

Is there some way that WordPress manages the scripts differently? I dunno, but the take away message here is to make sure and test your scripts to see how they act in various circumstances.

Posted in javascript, Plugins, WordPress | Tagged , , , | Leave a comment

Javascript Plugin: InnerFade with jQuery

Posted on 10 January 2012 by axe

Fade elements in and out with the InnerFade javascript plugin. Its purpose is to fade “any element inside a container in and out” and it relies on jQuery to do its magic. InnerFade is a lightweight plugin of only 8 kb, so it won’t bog down your pages.

Any group of elements can be faded in and out with the InnerFade plugin as long as they are inside a container that is targeted by the first line of the script. Example elements that can be faded in and out are links in an unordered or ordered list, textual list items, or paragraphs in a div.

  • A. Eat Right – It’s the easiest medicine to take.
  • B. Buy Less Stuff – You don’t really need it, do you?
  • C. Recycle Everything – Save the Earth from humans.
  • D. Laugh Every Day – It helps to keep things in perspective.
  • E. Help One Another – Some day you’ll need a little help, so spread good karma.
  • F. Keep Smiling – It releases happy endorphins and makes you look great, too!
 

Target specific classes or ids for the right effect. Using the InnerFade plugin with jQuery is a simple way to show a countdown clock where one number fades out and the next one in the sequence fades in.

A news ticker, like the one above, can be created by fading in and out headlines for each news item. Each headline could be a link to the complete story. The headlines could be marked up as list items, like this list of good ideas:

<ul id="good_ideas">
<li>A. Eat Right - It's the easiest medicine to take.</li>
<li>B. Buy Less Stuff - You don't really need it, do you?</li>
<li>C. Recycle Everything - Save the Earth from humans.</li>
<li>D. Laugh Every Day - It helps to keep things in perspective.</li>
<li>E. Help One Another - Some day you'll need a little help, so spread good karma.</li>
<li>F. Keep Smiling - It releases happy endorphins and makes you look great, too!</li>
</ul>

The easiest way to use the InnerFade plug is to accept the default settings, as we did above, and call it with a minimum of effort like so:

jQuery(document).ready(function($) {
    $('#good_ideas').innerfade();
  });

There are only a handful of options and changing them is fairly simple. The type of animation can be set to ‘fade’ or ‘slide’. The speed of the fading or sliding effects is set in milliseconds or with the strings ‘slow’, ‘normal’, or ‘fast’. Timeout is the time between animations in milliseconds. The type of slideshow is set using the strings ‘sequence’, ‘random’, or ‘random_start’. The height of the container element can be set in px, em, %.

Default Settings:

animationtype: fade
speed: normal
timeout: 2000
type: sequence
containerheight: auto
runningclass: innerfade

Now that you know you can call the javascript plugin and use it with the default settings, try changing the settings for different effects. For example, try sliding the elements slowly in and out of the 45px tall container in random order with a 3 second pause.

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$(document).ready(
function() {
$('.group2fade').innerfade({
animationtype: slide,
speed: 'slow',
timeout: 3000,
type: 'random',
containerheight: '45px'
});
}
);

The InnerFade plugin handles all the hiding of elements until viewed, so without javascript enabled, the visitor will see everything on the page. Use a <noscript> method to offer alternative content to browsers with javascript turned off and put it in the html document just before the closing body tag.

InnerFade plugin can be used for simple slideshows too. The only caveat is to make sure images are of the same size or the bottom edges of larger pics will be seen behind the stack of images.

Posted in CSS, javascript, Plugins | Tagged , , , | 2 Comments