SOURCE

! function() {
    //封装方法，压缩之后减少文件大小
    function get_attribute(node, attr, default_value) {
        return node.getAttribute(attr) || default_value;
    }
    //封装方法，压缩之后减少文件大小
    function get_by_tagname(name) {
        return document.getElementsByTagName(name);
    }
    //获取配置参数
    function get_config_option() {
        var scripts = get_by_tagname("script"),
            script_len = scripts.length,
            script = scripts[script_len - 1];                        //当前加载的script
        return {
            l: script_len,                                           //长度，用于生成id用
            z: get_attribute(script, "zIndex", -20),                 //z-index
            o: get_attribute(script, "opacity", 0.7),                //opacity
            c: get_attribute(script, "color", "0,100,150"),          //color
            n: get_attribute(script, "count", 130)                   //count
        };
    }
    //设置canvas的高宽
    function set_canvas_size() {
        canvas_width = the_canvas.width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth, 
        canvas_height = the_canvas.height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
    }

    //绘制过程
    function draw_canvas() {
        context.clearRect(0, 0, canvas_width, canvas_height);
        //随机的线条和当前位置联合数组
        var all_array = [current_point].concat(random_lines);
        var e, i, d, x_dist, y_dist, dist;                          //临时节点
        //遍历处理每一个点
        random_lines.forEach(function(r) {
            r.x += r.xa, 
            r.y += r.ya,                                            //移动
            r.xa *= r.x > canvas_width || r.x < 0 ? -1 : 1, 
            r.ya *= r.y > canvas_height || r.y < 0 ? -1 : 1,        //碰到边界，反向反弹
            context.fillRect(r.x - 0.5, r.y - 0.5, 1, 1);           //绘制一个宽高为1的点
            for (i = 0; i < all_array.length; i++) {
                e = all_array[i];
                //不是当前点
                if (r !== e && null !== e.x && null !== e.y) {
                        x_dist = r.x - e.x,                         //x轴距离 l
                        y_dist = r.y - e.y,                         //y轴距离 n
                        dist = x_dist * x_dist + y_dist * y_dist;   //总距离, m
                    dist < e.max && (e === current_point && dist >= e.max / 2 && (r.x -= 0.03 * x_dist, r.y -= 0.03 * y_dist), //靠近的时候加速
                        d = (e.max - dist) / e.max, 
                        context.beginPath(), 
                        context.lineWidth = d / 2, 
                        context.strokeStyle = "rgba(" + config.c + "," + (d + 0.2) + ")", 
                        context.moveTo(r.x, r.y), 
                        context.lineTo(e.x, e.y), 
                        context.stroke());
                }
            }
            all_array.splice(all_array.indexOf(r), 1);

        }), frame_func(draw_canvas);
    }
    //创建画布，并添加到body中
    var the_canvas = document.createElement("canvas"),                 //画布
        config = get_config_option(),                                  //配置
        canvas_id = "c_n" + config.l,                                  //canvas id
        context = the_canvas.getContext("2d"), canvas_width, canvas_height, 
        frame_func = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function(func) {
            window.setTimeout(func, 1000 / 45);
        }, random = Math.random, 
        current_point = {
            x: null,               //当前鼠标x
            y: null,               //当前鼠标y
            max: 20000
        };
    the_canvas.id = canvas_id;
    the_canvas.style.cssText = "position:fixed;top:0;left:0;z-index:" + config.z + ";opacity:" + config.o;
    get_by_tagname("body")[0].appendChild(the_canvas);

    //初始化画布大小
    set_canvas_size(), window.onresize = set_canvas_size;

    //当时鼠标位置存储，离开的时候，释放当前位置信息
    window.onmousemove = function(e) {
        e = e || window.event, current_point.x = e.clientX, current_point.y = e.clientY;
    }, window.onmouseout = function() {
        current_point.x = null, current_point.y = null;
    };

    //随机生成config.n条线位置信息
    for (var random_lines = [], i = 0; config.n > i; i++) {
        var x = random() * canvas_width,                     //随机位置
            y = random() * canvas_height,
            xa = 2 * random() - 1,                           //随机运动方向
            ya = 2 * random() - 1;
        random_lines.push({
            x: x,
            y: y,
            xa: xa,
            ya: ya,
            max: 6000                                        //沾附距离
        });
    }
    
    //0.1秒后绘制
    setTimeout(function() {
        draw_canvas();
    }, 100);
}();

body {
    background: #fafafa;
}