Javascript – how to add thumbnails to dots of slick slider mentioning the current slide

htmljavascriptjquery

I am currently working on a new project which required a slider. I have implemented slick JS for one of my project.

Now I need to add thumbnails which will appear when we hover the dots which will link to the slider

For example, click on first thumb and slider will advance to first slide,….click on third and slides to third slide.

HTML

    <html>
      <head>
        <title>My Now Amazing Webpage</title>
       <link rel="stylesheet" type="text/css" href="slick/slick.css"/>
       <link rel="stylesheet" type="text/css" href="slick/style.css"/>
      </head>
     <body>
<!-- THis is the slider code  -->
        <div class="center">
          <div><img  alt="slide 2" src="images/img1.jpg"></div>
          <div><img  alt="slide 2" src="images/img2.jpg"></div>
          <div><img  alt="slide 2" src="images/img3.jpg"></div>
          <div><img  alt="slide 2" src="images/img4.jpg"></div>
          <div><img  alt="slide 2" src="images/img5.jpg"></div>
        </div>

       <script type="text/javascript" src="slick/jquery-1.11.0.min.js"></script>
       <script type="text/javascript" src="slick/jquery-migrate-1.2.1.min.js"></script>
       <script type="text/javascript" src="slick/slick.min.js"></script> 

       <script type="text/javascript">
        $('.center').slick({

            centerMode: true,
            centerPadding: '60px',
            slidesToShow: 1,
            dots: !0,   /* It is for the navigation dots  */
            draggable: !1,
            responsive: [
             {
                 breakpoint: 768,
                 settings: {
                     arrows: false,
                     centerMode: true,
                     centerPadding: '40px',
                     slidesToShow: 1
                 }
             },
            {
                breakpoint: 480,
                settings: {
                    arrows: false,
                    centerMode: true,
                    centerPadding: '40px',
                    slidesToShow: 1
                }
            }
            ]
        });
      </script>
    </body>
</html>

Best Answer

You may replace dots with custom thumbnails. You would need to add thumbnails somewhere (for example, in a hidden div inside the image slide wrapper. See the code for reference:

$('.slideme').slick({
  dots: true,
  customPaging: function(slider, i) { 
    // this example would render "tabs" with titles
    return '<button class="tab">' + $(slider.$slides[i]).find('.slide-title').text() + '</button>';
  },
});

You would also need tweak up the native Slick pager css to remove dots and add more space and styles for your thumbnails

How to use:

You can be sure that the function given above returns correct answer at the moment of time when it is called, but what about tracking element's visibility as an event?

Place the following code at the bottom of your <body> tag:

function onVisibilityChange(el, callback) {
    var old_visible;
    return function () {
        var visible = isElementInViewport(el);
        if (visible != old_visible) {
            old_visible = visible;
            if (typeof callback == 'function') {
                callback();
            }
        }
    }
}

var handler = onVisibilityChange(el, function() {
    /* Your code go here */
});


// jQuery
$(window).on('DOMContentLoaded load resize scroll', handler);

/* // Non-jQuery
if (window.addEventListener) {
    addEventListener('DOMContentLoaded', handler, false);
    addEventListener('load', handler, false);
    addEventListener('scroll', handler, false);
    addEventListener('resize', handler, false);
} else if (window.attachEvent)  {
    attachEvent('onDOMContentLoaded', handler); // Internet Explorer 9+ :(
    attachEvent('onload', handler);
    attachEvent('onscroll', handler);
    attachEvent('onresize', handler);
}
*/

If you do any DOM modifications, they can change your element's visibility of course.

Guidelines and common pitfalls:

Maybe you need to track page zoom / mobile device pinch? jQuery should handle zoom/pinch cross browser, otherwise first or second link should help you.

If you modify DOM, it can affect the element's visibility. You should take control over that and call handler() manually. Unfortunately, we don't have any cross browser onrepaint event. On the other hand that allows us to make optimizations and perform re-check only on DOM modifications that can change an element's visibility.

Never Ever use it inside jQuery $(document).ready() only, because there is no warranty CSS has been applied in this moment. Your code can work locally with your CSS on a hard drive, but once put on a remote server it will fail.

After DOMContentLoaded is fired, styles are applied, but the images are not loaded yet. So, we should add window.onload event listener.

We can't catch zoom/pinch event yet.

The last resort could be the following code:

/* TODO: this looks like a very bad code */
setInterval(handler, 600);

You can use the awesome feature pageVisibiliy of the HTML5 API if you care if the tab with your web page is active and visible.

TODO: this method does not handle two situations:

Overlapping using z-index.
Using overflow-scroll in element's container.
Try something new - The Intersection Observer API explained.

Best Answer

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