代码特效（html+css+JavaScript）

DOCTYPE html>
html>
    head>
        meta charset="utf-8">
        title>北冥想当黑客啦title>
        style>
            *{padding: 0;margin: 0;}
            html{pverflow:hidden}
        style>
    head>
    body>
        canvas id = "canvas" style="background: #111;">canvas>
        script type="text/javascript">
            window.onload = function(){
                //获取画布对象
                var canvas = document.getElementById("canvas");
                //获取画布的上下文
                var context = canvas.getContext("2d");
                //获取浏览器屏幕的宽高
                var W = window.innerWidth;
                var H = window.innerHeight;
                //设置canvas宽高
                canvas.width = W;
                canvas.height = H;
                //每个文字的字体大小
                var fontSize = 16;
                //计算列
                var colunms = Math.floor(W/fontSize);
                //记录每列文字的y轴坐标
                var drops = [];
                //给每一个文字初始化一个起始点的位置
                for(var i = 0; icolunms; i++){
                    drops.push(0);
                }
                
                //运动的文字
                var str = "i love you";
                //4:fillText(str,x,y);原理就是去更改y的坐标位置
                //绘图的函数
                function draw(){
                    context.fillStyle = "rgba(0,0,0,0.05)";
                    context.fillRect(0,0,W,H);
                    //给字体设置样式
                    context.font = "700 "+fontSize +"px 微软雅黑";
                    //给字体添加颜色
                    context.fillStyle = "#00cc33";//可以rgb、hsl、标准色、十六制颜色
                    //写入画布中
                    for(var i = 0; icolunms; i++){
                        var index = Math.floor(Math.random() * str.length);
                        var x = i*fontSize;
                        var y = drops[i] * fontSize;
                        context.fillText(str[index],x,y);
                        //如果改变时间，肯定就是改变每次他的起点
                        if(y >= canvas.height && Math.random() > 0.99){
                            drops[i] = 0;
                        }
                        drops[i]++;
                    }
                }
                
                function randColoe(){
                    var r = Math.floor(Math.random() * 256);
                    var g = Math.floor(Math.random() * 256);
                    var b = Math.floor(Math.random() * 256);
                    return "rgb(" + r + "," + g + "," + b + ")";
                }
                
                draw();
                setInterval(draw,30);
            }
        script>
        
        
    body>
html>