js实现网页特效（利用原生js模拟直播弹幕滚动效果）

<li class="move_video_content">
    <li class="video_content">
        <li class="video_li" id="video_view"></li>
        <li class="scroll_content">
            <ul class="scroll_ul" id="scroll_ul_id"></ul> 
        </li>
    </li>
    <li class="input_content">
            <input type="text" class="input_text" maxlength="30" placeholder="请输入要发送的弹幕" id="input_text_id">
            <button type="button" class="button_btn" id="send_btn">发送</button>
    </li>
</li>

let inputText = document.getElementById("input_text_id");//input输入框
let scrollContent = document.getElementById("scroll_ul_id");//侧边聊天栏
let videoView = document.getElementById("video_view");//视频区域
let videoWidth = videoView.offsetWidth;//直播区域的总宽度
let listHeight = videoView.offsetHeight/10;//每一层直播区域的高度
let listTopNum = [0,1,2,3,4,5,6,7,8,9];//将直播区域的高度分成10层
document.getElementById("send_btn").addEventListener("click",function(){//监听发送按钮
    let value = inputText.value;//获取输入框的值
    if(!value) return;
    appendDom(value);//将输入框的值插入到滚动聊天中
    createVideoBulletChatDom(value);//将输入框的值插入到弹幕中
    inputText.value = '';//清空输入框
    scrollContent.scrollTop = scrollContent.scrollHeight;//自动滚动到底部
})
function appendDom(value){//将输入框的值插入到滚动聊天中
    let li = document.createElement("li");
    li.setAttribute("class","scroll_li");
    li.innerHTML = value;
    scrollContent.appendChild(li);
}
let speedArr = ['normal','fast','faster'];
function createVideoBulletChatDom(value){//将输入框的值插入到弹幕中
    let num = listTopNum[Math.floor((Math.random()*listTopNum.length))];
    let p = document.createElement("p");
    p.setAttribute("class","video_p");
    p.style.top = (num * 60) + "px";
    p.style.left = videoWidth + "px";
    p.innerHTML = value;
    videoView.appendChild(p);
    let speed = speedArr[Math.floor((Math.random()*speedArr.length))];
    Animate(p,speed);//滚动动画
}
let animateType = {
    'normal':5,
    'fast':10,
    'faster':15
}
function Animate(dom,speed){//滚动动画
    let domWidth = dom.offsetWidth;//当前弹幕元素的宽度
    let distance = videoWidth;//直播区域的总宽度
    speed ? speed : 'normal';
    let interval = animateType[speed]
    let timer = setInterval(function(){
            distance -= interval;
            dom.style.left = distance + 'px';
            if(distance <= -domWidth){
                clearInterval(timer);
                videoView.removeChild(dom);//清除已经滚动出屏幕的标签
            }
    },50)
}