console 命令行工具 X clear
console
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Code</title>
    <style>
        body{
            margin: 0;
            overflow: hidden;
        }
    </style>
</head>

<body>
<canvas id="myCanvas"></canvas>
<script>
    const width = document.getElementById("myCanvas").width = 1920;//screen.availWidth;
    const height = document.getElementById("myCanvas").height = 1080;//screen.availHeight;
    const ctx = document.getElementById("myCanvas").getContext("2d");
    const arr = Array(Math.ceil(width / 10)).fill(0);
    const str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".split("");

function rain() {
    ctx.fillStyle = "rgba(0,0,0,0.05)";
    ctx.fillRect(0, 0, width, height);
    ctx.fillStyle = "#0f0";
    arr.forEach(function (value, index) {
        ctx.fillText(str[Math.floor(Math.random() * str.length)], index * 10, value + 10);
        arr[index] = value >= height || value > 8888 * Math.random() ? 0 : value + 10;
    });
}

setInterval(rain, 30);
</script>
</body>
</html>