<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
*{
padding: 0;
margin: 0;
overflow: hidden;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script src="./code_rain.js"></script>
</body>
</html>
var canvas = document.querySelector('canvas');
console.log(canvas);
var ctx = canvas.getContext('2d');
canvas.width = screen.availWidth;
canvas.height = screen.availHeight;
var str = 'QWERTYUIOPASDFGHJKLZXCVBNM1234567890'.split('');
var arr = Array(Math.ceil(canvas.width / 10)).fill(0);
console.log(arr);
var rain = function () {
ctx.fillStyle = 'rgba(0,0,0,0.05)';
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = '#0f0';
arr.forEach(function (item, index) {
console.log(item, index);
ctx.fillText(str[Math.floor(Math.random() * str.length)], index * 10, item + 10); //填充文字，x轴位置，y轴位置
arr[index] = item > canvas.height || item > 10000 * Math.random() ? 0 : item + 10;
});
};
setInterval(rain, 60);
效果（真实效果为动态）：
标签：canvas,代码,ctx,arr,item,var,Math From： https://www.cnblogs.com/zhaofen/p/17802610.html