jcarouselLazyLoading plugin

Adds lazy loading to jcarousel.

The plugin halts slide scrolling until the next slide is loaded. Scrolling will happen once the next slide is ready. But if the next slide is at least partially visible (e.g. when swipe gestures are used), the scrolling will not be postponed.

Features

• configurable
• works with any content (video, ajax, images, picture)
• easy to use

Requirments

• jQuery
• jquery.jcarousel-core.js (minimum), you also may use the bundle version: jquery.jcarousel.js

How to use

To use the plugin include jquery, jcarousel and jcarouselLazyLoading source files into your HTML document:

<script type="text/javascript" src="js/jquery.min.js"></script>
<script type="text/javascript" src="js/jquery.jcarousel.min.js"></script>
<script type="text/javascript" src="js/jquery.jcarousel-lazyloading.min.js"></script>

By default plugin works with images and data-src attribute. Or if you use srcset or picture tag you should use data-srcset and data-sizes attributes. You can see "Picture" example. Also, until images are loaded jcarousel won't get correct slide width.
Therefore you should set the width for all slides or set width and height attributes for lazy images.

<div class="jcarousel">
    <ul>
        <li><img data-src="http://fakeimg.pl/600x400/ccc/?text=slide1" width="600" height="400" alt=""></li>
        <li><img data-src="http://fakeimg.pl/600x400/bbb/?text=slide2" width="600" height="400" alt=""></li>
        <li><img data-src="http://fakeimg.pl/600x400/aaa/?text=slide3" width="600" height="400" alt=""></li>
        <li><img data-src="http://fakeimg.pl/600x400/999/?text=slide4" width="600" height="400" alt=""></li>
        <li><img data-src="http://fakeimg.pl/600x400/888/?text=slide5" width="600" height="400" alt=""></li>
        <li><img data-src="http://fakeimg.pl/600x400/777/?text=slide6" width="600" height="400" alt=""></li>
    </ul>
</div>

and init the plugin:

$('.jcarousel')
    .jcarousel()             // init jcarousel
    .jcarouselLazyLoading(); // init jcarouselLazyLoading

That's all =)

Options

{
    preventScroll: true, // default: true. If set false then jcarousel scroll will not be prevents
    waitFunction: function($slides, callback, isScrollPrevented) { // default: function that is written below
        // $slides: contains slides which will be visible after scroll
        // callback: contains function which you should call when all content in $slides is loaded
        // isScrollPrevented: boolean parameter. If true then method scroll was canceled
        // and waiting when callback function will be called. For example you may use it for cancel "show content" animation.
        var i = 0;
        var $lazyImages = $slides.find('img[data-src]');

        $lazyImages.toggleClass('non-transition', !!isScrollPrevented);
        $lazyImages.each(function() {
            var $img = $(this);
            var src = $img.attr('data-src');
            $img.addClass('loading');
            $img.attr('src', src).removeAttr('data-src');
        });
        wait();

        function wait() {
            i++;
            if ($.jCarousel.isImagesLoaded($slides)) {
                callback();
                $lazyImages.removeClass('loading');
            } else if (i <= 100) { // wait maximum 10 seconds
                setTimeout(wait, 100);
            } else {
                callback();
                $lazyImages.removeClass('loading');
            }
        }
    }
}

You can use waitFunction to wait for any content.
Also you may use any third-party plugin for content loading in waitFunction(e.g. imagesLoaded https://github.com/desandro/imagesloaded)

##License Copyright (c) 2016 Evgeniy Pelmenev. Released under the MIT license.