How does HTML5 canvas implement code flow waterfall? (with code)

This article will share with you the specific code of HTML5 canvas code flow waterfall. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

Write the canvas code in the js part, with detailed comments

html part:

A canvas element:

<canvas id="canvas" ></canvas>

css part:

<style>
  *{
   padding: 0;
   margin: 0;
  }
  canvas{
   background-color: #111;
  }
  body{
   overflow: hidden;
  
  }
</style>

js part

<script>
  var canvas = document.getElementById(&#39;canvas&#39;);
  var context = canvas.getContext(&#39;2d&#39;);
  // 获取浏览器的宽度和高度
  var w = window.innerWidth;
  var h = window.innerHeight;
  // 设置canvas的宽高
  canvas.width = w;
  canvas.height = h;
  // 每个文字的大小
  var fontSize = 16;
  // 一共可以有多少列文字
  var col = Math.floor(w / fontSize);
  // 记录每列文字的y轴坐标
  var cpy = [];
  for(var i = 0;i< col; i++)
  {
   cpy[i] = 1;
  }
  //定义文字
  var str = "Javascriphafhsdhfsfsf{}";
  // 绘制
  draw();
  setInterval(draw,30);
  function draw(){
   context.beginPath();
   // 背景填充颜色
   context.fillStyle = "rgba(0,0,0,0.05)";
   context.fillRect(0,0,w,h);
   // 设置字体大小
   context.font = fontSize +"px bold 微软雅黑 ";
   // 设置字体颜色
   context.fillStyle = "#00cc33";
   for(var i = 0; i < col;i++)
   {
    var index = Math.floor(Math.random()*str.length);
    var x = i*fontSize;
    var y = cpy[i]*fontSize;
    context.fillText(str.charAt(index),x,y);
    if(y >= h && Math.random()> 0.99)// 出现时间延迟的效果
    {
     cpy[i]=0;// 只要Math.random> 0.99 时才纵坐标从0开始写字
    }
    cpy[i]++;// 数组值加一，以便下一次写的字在下面一行
   }
  }
</script>

Dynamic renderings:

More cool special effects , recommended visit: js special effects collection!

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