Native JS to implement breathing carousel

Today I will share with you a breathing carousel implemented with native JS. The effect is as follows:

The following is the code implementation, you are welcome to copy and paste.

<!DOCTYPE html>
<html>
 
<head>
    <meta charset="utf-8" />
    <title>Native JS to implement breathing carousel</title>
    <style>
        ul {
            margin: 0;
            padding-left: 0;
        }
 
        li {
            list-style: none;
        }
 
        img {
            border: none;
        }
 
        #main {
            width: 280px;
            height: 330px;
            overflow: hidden;
            position: relative;
            margin: 20px auto 0 auto;
        }
 
        #main ul {
            position: absolute;
            left: 0;
        }
 
        #main ul li {
            width: 280px;
            height: 330px;
            float: left;
            position: absolute;
            filter:alpha(opacity=0);
            opacity: 0;
        }
 
        #btn {
            line-height: 14px;
            text-align: center;
            background: #eeeeee;
            width: 280px;
            margin: 10px auto 0 auto;
            display: flex;
            flex-direction: row;
            justify-content: space-around;
            align-items: center;
        }
 
        #btn a {
            display: inline-block;
            width: 14px;
            height: 14px;
            text-decoration: none;
            line-height: 12px;
            text-align: center;
            border-radius: 7px;
        }
 
        #btn a.index {
            background-color: #ccc;
        }
 
        #btn a.active {
            background-color: red;
        }
    </style>
    <script type="text/javascript" src="js/move.js"></script>
    <script>
        window.onload = function () {
            var oMain = document.getElementById('main');
            var oUl = oMain.getElementsByTagName('ul')[0];
            var aLi = oUl.getElementsByTagName('li');
 
            var oBtn = document.getElementById('btn');
            var aA = oBtn.getElementsByTagName('a');
 
            var iNow = 1;
            var iNow2 = 1;
            var bBtn = true;
            var num = 3;
            var timer = null;
 
            oUl.style.width = aLi.length * aLi[0].offsetWidth + 'px';
 
            aA[0].onclick = function () {
                if (bBtn) {
                    clearInterval(timer);
                    timer = setInterval(autoPlay, 3000);
                    for (var i = 0; i < aLi.length; i++) {
                        aLi[i].style.position = 'relative';
                        aLi[i].style.filter = 'alpha(opacity=100)';
                        aLi[i].style.opacity = 1;
                    }
                    oUl.style.left = -(iNow - 1) * aLi[0].offsetWidth + 'px';
                    if (iNow == 1) {
                        iNow = aLi.length;
                        aLi[aLi.length - 1].style.position = 'relative';
                        aLi[aLi.length - 1].style.left = -aLi.length * aLi[0].offsetWidth + 'px';
                    } else {
                        iNow--;
                    }
                    iNow2--;
                    toRun();
                    bBtn = false;
                }
            };
            aA[aA.length - 1].onclick = function () {
                if (bBtn) {
                    clearInterval(timer);
                    timer = setInterval(autoPlay, 3000);
                    for (var i = 0; i < aLi.length; i++) {
                        aLi[i].style.position = 'relative';
                        aLi[i].style.filter = 'alpha(opacity=100)';
                        aLi[i].style.opacity = 1;
                    }
                    oUl.style.left = -(iNow - 1) * aLi[0].offsetWidth + 'px';
                    if (iNow == aLi.length) {
                        iNow = 1;
                        aLi[0].style.position = 'relative';
                        aLi[0].style.left = aLi.length * aLi[0].offsetWidth + 'px';
                    } else {
                        iNow++;
                    }
                    iNow2++;
                    toRun();
                    bBtn = false;
                }
            };
 
            for (var i = 1; i < aA.length - 1; i++) {
                aA[i].index = i;
                aA[i].onclick = function () {
                    clearInterval(timer);
                    timer = setInterval(autoPlay, 3000);
                    iNow = this.index;
                    iNow2 = this.index;
                    toShow();
                };
            };
 
            function toRun() {
                for (var i = 1; i < aA.length - 1; i++) {
                    aA[i].className = 'index';
                }
                aA[iNow].className = 'active';
 
                startMove(oUl, { left: -(iNow2 - 1) * aLi[0].offsetWidth }, function () {
                    if (iNow == 1) {
                        aLi[0].style.position = 'relative';
                        aLi[0].style.left = 0;
                        oUl.style.left = 0;
                        iNow2 = 1;
                    } else if (iNow == aLi.length) {
                        aLi[aLi.length - 1].style.position = 'relative';
                        aLi[aLi.length - 1].style.left = 0;
                        oUl.style.left = -(aLi.length - 1) * aLi[0].offsetWidth + 'px';
                        iNow2 = aLi.length;
                    }
 
                    for (var i = 0; i < aLi.length; i++) {
                        aLi[i].style.position = 'absolute';
                        aLi[i].style.filter = 'alpha(opacity=0)';
                        aLi[i].style.opacity = 0;
                    }
                    oUl.style.left = 0;
                    aLi[iNow2 - 1].style.zIndex = num++;
                    aLi[iNow2 - 1].style.filter = 'alpha(opacity=100)';
                    aLi[iNow2 - 1].style.opacity = 1;
 
                    bBtn = true;
                });
            };
 
            function toShow() {
                for (var i = 1; i < aA.length - 1; i++) {
                    aA[i].className = 'index';
                }
                for (var i = 0; i < aLi.length; i++) {
                    startMove(aLi[i], { opacity: 0 });
                }
                aA[iNow].className = 'active';
                startMove(aLi[iNow - 1], { opacity: 100 }, function () {
                    aLi[iNow - 1].style.zIndex = num++;
 
                });
            }
 
            timer = setInterval(autoPlay, 3000);
 
            function autoPlay() {
                if (iNow == aLi.length) {
                    iNow = 1;
                    iNow2 = 1;
                } else {
                    iNow++;
                    iNow2++;
                }
 
                toShow();
            }
        };
    </script>
</head>
 
<body>
    <div id="main">
        <ul>
            <li style="z-index:2; filter:alpha(opacity=100); opacity:1;">
                <a>
                    <img src="images/0.jpg" />
                </a>
            </li>
            <li>
                <a>
                    <img src="images/1.jpg" />
                </a>
            </li>
            <li>
                <a>
                    <img src="images/2.jpg" />
                </a>
            </li>
            <li>
                <a>
                    <img src="images/3.jpg" />
                </a>
            </li>
        </ul>
    </div>
    <div id="btn">
        <a class="prev" href="javascript:;">
            <a class="active" href="javascript:;">
        </a>
        <a class="index" href="javascript:;"></a>
        <a class="index" href="javascript:;"></a>
        <a class="index" href="javascript:;"></a>
        <a class="next" href="javascript:;">></a>
    </div>
</body>
 
</html>

The following is the code of the most important movement function move.js introduced in the above code:

function startMove(obj, json, fnEnd) {
    clearInterval(obj.timer);
    obj.timer = setInterval(function () {
        doMove(obj, json, fnEnd);
    }, 30);
}
function doMove(obj, json, fnEnd) {
    var iCur = 0;
    var attr = null;
    var bStop = true;
    for (attr in json) {
        if (attr == 'opacity') {
            if (parseInt(100 * getStyle(obj, attr)) == 0) {
                iCur = parseInt(100 * getStyle(obj, attr));
            } else {
                iCur = parseInt(100 * getStyle(obj, attr)) || 100;
            }
        } else {
            iCur = parseInt(getStyle(obj, attr)) || 0;
        }
        var iSpeed = (json[attr] - iCur) / 5;
        iSpeed = (iSpeed > 0) ? Math.ceil(iSpeed) : Math.floor(iSpeed);
        if (json[attr] != iCur) {
            bStop = false;
        }
        if (attr == 'opacity') {
            obj.style.filter = 'alpha(opacity=' + (iCur + iSpeed) + ')';
            obj.style.opacity = (iCur + iSpeed) / 100;
        } else {
            obj.style[attr] = iCur + iSpeed + 'px';
        }
    }
    if (bStop) {
        clearInterval(obj.timer);
        if (fnEnd) {
            fnEnd.call(obj);
        }
    }
}
function stopMove(obj) {
    clearInterval(obj.timer);
}
function getStyle(obj, attr) {
    if (obj.currentStyle) {
        return obj.currentStyle[attr];
    } else {
        return getComputedStyle(obj)[attr];
    }
}

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.

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