老师，左按钮的效果如何实现，而且右按钮点第一次的时候没有动画效果，是怎么回事

来源：3-2 项目作业

一心励志当码农

2021-06-08 10:15:27

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    font-size: 32px;
    color: #696868;
    text-align: center;
    line-height: 42px;
}
.news .up .bdright {
    width: 513px;
    height: 0;
    border-bottom: 1px solid #9B9B9B;
    position: absolute;
    top:42px;
    right:0;
}
.news .up .entitle {
    width: 105px;
    height: 24px;
    margin: 0 auto;
    position: absolute;
    top:43px;
    left: 50%;
    margin-left: -52px;
    font-size: 18px;
    color: #9B9B9B;
    text-align: center;
    line-height: 24px;
}
.news .up .bdbox {
    width: 93px;
    height: 3px;
    left: 50%;
    margin-left: -46px;
    position: absolute;
    top:82px;
    background-color: #0058AA;
}
.news .under {
    width: 1155px;
    height: 188px;
    padding-top: 70px;
    position: relative;
}
.news .under .clearfix .one {
    width: 503px;
    height: 109px;
}
.news .under .clearfix div.xuhao {
    float: left;
    width: 65px;
    height: 65px;
    text-align: center;
    line-height: 65px;
    font-size: 40px;
    color: #FFFFFF;
    background-image: url(../images/talk-bg.png);
    margin-right: 38px;  
    position: relative;
    top:20px;
}
.news .under .clearfix div.xuhao:hover {
    animation: move 0.4s ease 0s alternate infinite;
}
@keyframes move {
    from {
        top:20px;
    }
    to {
        top:10px;
    }
}

.news .under .clearfix dt.title {
    float: left;
    width: 84px;
    height: 28px;
    font-size: 21px;
    color: #4A4A4A;
    text-align: center;
    margin-bottom: 12px;

}
.news .under .clearfix dd.text {
    float: left;
    width: 400px;
    height: 69px;
    font-size: 18px;
    color: #4A4A4A;
}
.news .under .clearfix .two {
    width: 503px;
    height: 109px;
    position: absolute;
    top: 70px;
    right: 74px;
}
.news .under .clearfix .three {
    width: 503px;
    height: 221px;
    position: absolute;
    top: 215px;
    left: 0px; 
    margin-bottom: 50px;  
}
.news .under .clearfix .four {
    width: 503px;
    height: 109px;
    position: absolute;
    top: 215px;
    right: 74px;
    margin-bottom: 50px;
}

/* footer区域 */
.telmessage {
    width: 100%;
    height: 210px;
    background-color: #06142F;
    position: relative;
}

.telmessage .logo {
    width: 144px;
    height: 63px;
    font-size: 48px;
    color: #FFFFFF;
    line-height: 63px;
    position: absolute;
    top:74px;
    left:360px;
}
.telmessage .tel {
    width:191px;
    height: 40px;
    position: absolute;
    top:53px;
    left:605px;
    font-size: 16px;
    color: #FFFFFF;
    line-height: 40px;
}
.telmessage .wangzhi {
    width:207px;
    height: 40px;
    position: absolute;
    top:93px;
    left:605px;
    font-size: 16px;
    color: #FFFFFF;
    line-height: 40px;
}
.telmessage .email {
    width:199px;
    height: 40px;
    position: absolute;
    top:135px;
    left:605px;
    font-size: 16px;
    color: #FFFFFF;
    line-height: 40px;
}
footer .banquan {
    width: 100%;
    height: 30px;
    background-color: #202C46;
    text-align: center;
    line-height: 30px;
    color: white;
    font-size: 14px;
}

(function () {
    //得到元素
    var rightbtn = document.getElementById('rightbtn');
    var leftbtn = document.getElementById('leftbtn');
    var bigbox = document.getElementById('bigbox');

    //设置正在显示的图片的序号
    var idx = 0;
    rightbtn.onclick = function () {
        idx++;
        bigbox.style.left = -221 * idx + 'px';
        if (idx > 5){
            bigbox.style.left = -1105 + 'px';
        }
    };

    leftbtn.onclick = function () {
        if (idx == 0){
            bigbox.style.left = 0 + 'px';
        }
    }

})();