I have a slideshow I've found online. It's quite a large slideshow and the images take a really long time to load and I've already reduced the file size. I was hoping someone could show me how I preload the images to hopefully make it load quickly.

I'm also having another problem when viewing on a mobile site, it seems to shrink the image. I need it to stay full size.

The code is below:

// Speed of the automatic slideshow
var slideshowSpeed = 4000;

// Variable to store the images we need to set as background
// which also includes some text and url's.
var photos = [ {
        "title" : "Stairs",
        "image" : "banner1.png",
        "url" : "http://www.sxc.hu/photo/1221065",
        "firstline" : "Going on",
        "secondline" : "vacation?"
    }, {
        "title" : "Office Appartments",
        "image" : "Karreman_Calendar1.jpg",
    "url" : "http://www.sxc.hu/photo/1221065",
        "firstline" : "Or still busy at",
        "secondline" : "work?"
    }, {
        "title" : "Mountainbiking",
        "image" : "Karreman_Calendar2.jpg",
        "url" : "http://www.sxc.hu/photo/1221065",
        "firstline" : "Get out and be",
        "secondline" : "active"
    }, {
        "title" : "Mountains Landscape",
        "image" : "Karreman_Calendar3.jpg",
        "url" : "http://www.sxc.hu/photo/1271915",
        "firstline" : "Take a fresh breath of",
        "secondline" : "nature"
    }, {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar4.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    },

    {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar5.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    },
    {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar6.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    },

    {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar8.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    },
        {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar9.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    },

        {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar10.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    },

        {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar11.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    },

        {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar12.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    },

        {
        "title" : "Italian pizza",
        "image" : "Karreman_Calendar13.jpg",
        "url" : "http://www.sxc.hu/photo/1042413",
        "firstline" : "Enjoy some delicious",
        "secondline" : "food"
    }


];



$(document).ready(function() {

    // Backwards navigation
    $("#back").click(function() {
        stopAnimation();
        navigate("back");
    });

    // Forward navigation
    $("#next").click(function() {
        stopAnimation();
        navigate("next");
    });

    var interval;
    $("#control").toggle(function(){
        stopAnimation();
    }, function() {
        // Change the background image to "pause"
        $(this).css({ "background-image" : "url(images/btn_pause.png)" });

        // Show the next image
        navigate("next");

        // Start playing the animation
        interval = setInterval(function() {
            navigate("next");
        }, slideshowSpeed);
    });


    var activeContainer = 1;    
    var currentImg = 0;
    var animating = false;
    var navigate = function(direction) {
        // Check if no animation is running. If it is, prevent the action
        if(animating) {
            return;
        }

        // Check which current image we need to show
        if(direction == "next") {
            currentImg++;
            if(currentImg == photos.length + 1) {
                currentImg = 1;
            }
        } else {
            currentImg--;
            if(currentImg == 0) {
                currentImg = photos.length;
            }
        }

        // Check which container we need to use
        var currentContainer = activeContainer;
        if(activeContainer == 1) {
            activeContainer = 2;
        } else {
            activeContainer = 1;
        }

        showImage(photos[currentImg - 1], currentContainer, activeContainer);

    };

    var currentZindex = -1;
    var showImage = function(photoObject, currentContainer, activeContainer) {
        animating = true;

        // Make sure the new container is always on the background
        currentZindex--;

        // Set the background image of the new active container
        $("#headerimg" + activeContainer).css({
            "background-image" : "url(/karreman/slideshow/" + photoObject.image + ")",
            "display" : "block",
            "z-index" : currentZindex
        });

        // Hide the header text
        $("#headertxt").css({"display" : "none"});

        // Set the new header text
        $("#firstline").html(photoObject.firstline);
        $("#secondline")
            .attr("href", photoObject.url)
            .html(photoObject.secondline);
        $("#pictureduri")
            .attr("href", photoObject.url)
            .html(photoObject.title);


        // Fade out the current container
        // and display the header text when animation is complete
        $("#headerimg" + currentContainer).fadeOut(function() {
            setTimeout(function() {
                $("#headertxt").css({"display" : "block"});
                animating = false;
            }, 500);
        });
    };

    var stopAnimation = function() {
        // Change the background image to "play"
        $("#control").css({ "background-image" : "url(images/btn_play.png)" });

        // Clear the interval
        clearInterval(interval);
    };

    // We should statically set the first image
    navigate("next");

    // Start playing the animation
    interval = setInterval(function() {
        navigate("next");
    }, slideshowSpeed);
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LastMitch

I have a slideshow I've found online. It's quite a large slideshow and the images take a really long time to load and I've already reduced the file size. I was hoping someone could show me how I preload the images to hopefully make it load quickly.

@kimmi_baby

You can reduce the images size by doing that it will load quickly.

You can used photoshop to optimize images so it is light, then it will go smoothly.

I never seen or heard any jQuery/javascript code that scale an image to appear/load quickly.

It's usually animation feature like that code you provided above.

Hi kimmi_baby,

There is nothing to do with script, Image optimization should be done manually.

for Preloader just add the preloader image as background in gallery container div. this will helps