這次帶給大家用JS代碼做出彈幕效果,用JS代碼做出彈幕效果的注意事項有哪些,下面就是實戰案例,一起來看一下。
實作原理
1、設定展示彈幕元素位置屬性為relative
2、動態建立彈幕元素,位置屬性設定absolute,left為展示寬度
3、隨機設定彈幕元素top值
4、隨機產生彈幕元素移動速率,修改left值
隨機顏色
第一種實現let color = '#' + Math. floor(Math.random() * 0xffffff).toString(16);
#第二種實作let color = '#' + Math.floor(Math.random() * 1677215).toString(16) ;
第三種實作let r = Math.floor(Math.random()*256);let g = Math.floor(Math.random()*256);let b = Math.floor( Math.random()*256);let color = `rgb(${r},${g},${b})`;
隨機速率
50 * +Math.random().toFixed(2)
程式碼
//html
<div class="container"> <div id="content" class="content"></div> <div class="content-opt"> <div id="content-text" class="content-text"></div> <div class="content-input"> <input id="text" type="text"> <button id="send">发送</button> </div> </div> </div>
//css
* { box-sizing: border-box; outline: none; } p { margin: .5em; word-break: break-all; } .container { position: relative; width: 700px; height: 500px; margin: auto; padding-right: 200px; } .content { width: 100%; height: 100%; border: 1px solid #ccc;} .content-opt { position: absolute; top: 0; right: 0; width: 200px; height: 100%; } .content-text { height: calc(100% - 30px); margin-bottom: 30px; border: 1px solid #ccc; overflow: auto; } .content-input { position: absolute; bottom: 0; width: 100%; height: 30px; border: 1px solid #ccc;} .content-input input { width: 70%; padding: 2px; border-radius: 5px; } .content-input button { padding: 3px 10px; border: none; border-radius: 5px; background: rgb(90, 154, 214); }
//js
(function () { class Barrage { constructor(id) { this.domList = []; this.dom = document.querySelector('#' + id); if (this.dom.style.position == '' || this.dom.style.position == 'static') { this.dom.style.position = 'relative'; } this.dom.style.overflow = 'hidden'; let rect = this.dom.getBoundingClientRect(); this.domWidth = rect.right - rect.left; this.domHeight = rect.bottom - rect.top; } shoot(text) { let div = document.createElement('div'); div.style.position = 'absolute'; div.style.left = this.domWidth + 'px'; div.style.top = (this.domHeight - 20) * +Math.random().toFixed(2) + 'px'; div.style.whiteSpace = 'nowrap'; div.style.color = '#' + Math.floor(Math.random() * 0xffffff).toString(16); div.innerText = text; this.dom.appendChild(div); let roll = (timer) => { let now = +new Date(); roll.last = roll.last || now; roll.timer = roll.timer || timer; let left = div.offsetLeft; let rect = div.getBoundingClientRect(); if (left < (rect.left - rect.right)) { this.dom.removeChild(div); } else { if (now - roll.last >= roll.timer) { roll.last = now; left -= 3; div.style.left = left + 'px'; } requestAnimationFrame(roll); } } roll(50 * +Math.random().toFixed(2)); } } let barage = new Barrage('content'); function appendList(text) { let p = document.createElement('p'); p.innerText = text; document.querySelector('#content-text').appendChild(p); } document.querySelector('#send').onclick = () => { let text = document.querySelector('#text').value; barage.shoot(text); appendList(text); }; const textList = ['弹幕', '666', '233333333', 'javascript', 'html', 'css', '前端框架', 'Vue', 'React', 'Angular', '测试弹幕效果' ]; textList.forEach((s) => { barage.shoot(s); appendList(s); }) })()
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