h5实现撒花效果

最近在业务开发中遇到一个问题，需要实现撒花或者下雨的效果,所以结合了keyframes和animation实现了撒花效果，封装了一下，copy代码，开箱即用

js封装

class AnimationItems {
  constructor() {
    this.timer = null;
    this.status = false;
    this.num = 3;// 每秒出现花瓣个数
    this.times = 3; // 每个出现时间
    this.start = function () {
      const body = document.getElementsByTagName('body')[0];
      const keyframes = `@keyframes animation_move {
        0% {
          top: 0;
          opacity: 0.1;
        }
        20% {
          opacity: 1;
          }
        100% {
          top: 100vh;
          }
        }`;
      const style = document.createElement('style');
      style.type = 'text/css';
      style.innerHTML = keyframes;
      document.getElementsByTagName('head')[0].appendChild(style)
      this.status = false;
      this.timer = setInterval(() => {
        const removeE = document.getElementsByClassName('animation_move');
        const n = this.num * this.times;
        if (removeE.length > n-1) {
          body.removeChild(removeE[0]);
        }
        const ran = Math.random()*10 * 0.72; //屏幕宽度采用720px，建议使用rem动态计算
        const e = document.createElement('div');
        e.style.width = '50px';
        e.style.height = '50px';
        e.style.background = `url('https://raw.githubusercontent.com/ZGL520/MyImages/master/rose.jpg') no-repeat`;
        e.style.backgroundSize = '50px';
        e.style.position = 'fixed';
        e.style.top = '100px';
        e.style.left = `${ran * 100}px`;
        e.style.animation = `animation_move ${3}s infinite ease-in`;
        e.style.zIndex = 1000;
        e.className = 'animation_move';
        if (!this.status) {
          body.appendChild(e);
        }
      }, 1000 / this.num);

    };
    this.stop = function () {
      this.status = true;
      clearInterval(this.timer);
      const els = document.getElementsByClassName('animation_move');
      const body = document.getElementsByTagName('body')[0];
      const n = this.num * this.times;
      for (let i = 0; i < n; i++) {
        if (els.length < 1) return;
        body.removeChild(els[0]);
      }
    };
  }
}

使用

    const animation = new AnimationItems();
    animation.start();//开始
    setTimeout(() => {
      animation.stop();//停止
    }, 10000)

效果