[Antonjrjr]

Ребят , есть код галереи с миниатюрами , нужно чтобы при клике на стрелки плавно менялись картинки кажется с помощью css свойства transition. но что писать в js

<div class="gallery__wrapper">
            <div class="image-main__wrapper">
                <img class="image-main" src="images/fullsize/1.jpg" id="image-main">
                    <div class="arrowleft"><img src="images/left.jpg" id="arrowleft"/></div>
                    <div class="arrowright"><img src="images/right.jpg" id="arrowright"/></div>
                <div class="image-thumbnails__wrapper">
                    <ul class="thumbnails">
                        <li><img id="thumb-1" class="gallery__img" src="images/thumbs/1.jpg" data-full-url="images/fullsize/1.jpg"/></li>
                        <li><img id="thumb-2" class="gallery__img" src="images/thumbs/2.jpg" data-full-url="images/fullsize/2.jpg"/></li>
                        <li><img id="thumb-3" class="gallery__img" src="images/thumbs/3.jpg" data-full-url="images/fullsize/3.jpg"/></li>
                        <li><img id="thumb-4" class="gallery__img" src="images/thumbs/4.jpg" data-full-url="images/fullsize/4.jpg"/></li>
                        <li><img id="thumb-5" class="gallery__img" src="images/thumbs/5.jpg" data-full-url="images/fullsize/5.jpg"/></li>
                        <li><img id="thumb-6" class="gallery__img" src="images/thumbs/6.jpg" data-full-url="images/fullsize/6.jpg"/></li>
                        <li><img id="thumb-7" class="gallery__img" src="images/thumbs/7.jpg" data-full-url="images/fullsize/7.jpg"/></li>
                        <li><img id="thumb-8" class="gallery__img" src="images/thumbs/8.jpg" data-full-url="images/fullsize/8.jpg"/></li>
                        <li><img id="thumb-9" class="gallery__img" src="images/thumbs/9.jpg" data-full-url="images/fullsize/9.jpg"/></li>
                        <li><img id="thumb-10" class="gallery__img" src="images/thumbs/10.jpg" data-full-url="images/fullsize/10.jpg" /></li>
                        <li><img id="thumb-11" class="gallery__img" src="images/thumbs/11.jpg" data-full-url="images/fullsize/11.jpg"/></li>
                        <li><img id="thumb-12" class="gallery__img" src="images/thumbs/12.jpg" data-full-url="images/fullsize/12.jpg"/></li>
                        <li><img id="thumb-13" class="gallery__img" src="images/thumbs/13.jpg" data-full-url="images/fullsize/13.jpg"/></li>
                        <li><img id="thumb-14" class="gallery__img" src="images/thumbs/14.jpg" data-full-url="images/fullsize/14.jpg"/></li>
                    </ul>
                </div>
            </div>
        </div>
[JS]
 var thumbnails = Array.prototype.slice.call(document.querySelectorAll('.gallery__img'));
    function clickOnThumbnail(event) {
        document.querySelector('.image-main').src = this.dataset.fullUrl;
    }
    for (var i = 0; i < thumbnails.length; i++) {
        thumbnails[i].addEventListener('click', clickOnThumbnail);
    };

    ;(function arrows(){
        var leftArrow = document.getElementById('arrowleft'),
            rightArrow = document.getElementById('arrowright'),
            initImgNumber = 1;
        maxImgNum = 14;

        leftArrow.addEventListener('click', moveBackvard);
        rightArrow.addEventListener('click', moveForvard);

        function moveBackvard(){
            var image = document.getElementById('image-main');
            initImgNumber--;
            if (initImgNumber == 0){initImgNumber = maxImgNum};
            image.setAttribute('src', 'images/gallery/big/' + initImgNumber + '.jpg');
        };

        function moveForvard(){
            var image = document.getElementById('image-main');
            initImgNumber++;
            if (initImgNumber > maxImgNum){initImgNumber = 1};
            image.setAttribute('src', 'images/gallery/big/' + initImgNumber + '.jpg');
        };
    })();

[/JS]