一、下雪特效代码①
1 <script type="text/javascript"> 2 (function($){ 3 $.fn.snow = function(options){ 4 var $flake = $('<div id="snowbox" />').css({'position': 'absolute','z-index':'9999', 'top': '-50px'}).html('❄'), 5 documentHeight = $(document).height(), 6 documentWidth = $(document).width(), 7 defaults = { 8 minSize : 10, 9 maxSize : 20, 10 newOn : 1000, 11 flakeColor : "#AFDAEF" /* 此处可以定义雪花颜色，若要白色可以改为#FFFFFF */ 12 }, 13 options = $.extend({}, defaults, options); 14 var interval= setInterval( function(){ 15 var startPositionLeft = Math.random() * documentWidth - 100, 16 startOpacity = 0.5 + Math.random(), 17 sizeFlake = options.minSize + Math.random() * options.maxSize, 18 endPositionTop = documentHeight - 200, 19 endPositionLeft = startPositionLeft - 500 + Math.random() * 500, 20 durationFall = documentHeight * 10 + Math.random() * 5000; 21 $flake.clone().appendTo('body').css({ 22 left: startPositionLeft, 23 opacity: startOpacity, 24 'font-size': sizeFlake, 25 color: options.flakeColor 26 }).animate({ 27 top: endPositionTop, 28 left: endPositionLeft, 29 opacity: 0.2 30 },durationFall,'linear',function(){ 31 $(this).remove() 32 }); 33 }, options.newOn); 34 }; 35 })(jQuery); 36 $(function(){ 37 $.fn.snow({ 38 minSize: 5, /* 定义雪花最小尺寸 */ 39 maxSize: 50,/* 定义雪花最大尺寸 */ 40 newOn: 300 /* 定义密集程度，数字越小越密集 */ 41 }); 42 }); 43 </script>
二、下雪特效代码②
1 <script type="text/javascript"> 2 /* 控制下雪 */ 3 function snowFall(snow) { 4 /* 可配置属性 */ 5 snow = snow || {}; 6 this.maxFlake = snow.maxFlake || 200; /* 最多片数 */ 7 this.flakeSize = snow.flakeSize || 10; /* 雪花形状 */ 8 this.fallSpeed = snow.fallSpeed || 1; /* 坠落速度 */ 9 } 10 /* 兼容写法 */ 11 requestAnimationFrame = window.requestAnimationFrame || 12 window.mozRequestAnimationFrame || 13 window.webkitRequestAnimationFrame || 14 window.msRequestAnimationFrame || 15 window.oRequestAnimationFrame || 16 function(callback) { setTimeout(callback, 1000 / 60); }; 17 18 cancelAnimationFrame = window.cancelAnimationFrame || 19 window.mozCancelAnimationFrame || 20 window.webkitCancelAnimationFrame || 21 window.msCancelAnimationFrame || 22 window.oCancelAnimationFrame; 23 /* 开始下雪 */ 24 snowFall.prototype.start = function(){ 25 /* 创建画布 */ 26 snowCanvas.apply(this); 27 /* 创建雪花形状 */ 28 createFlakes.apply(this); 29 /* 画雪 */ 30 drawSnow.apply(this) 31 } 32 /* 创建画布 */ 33 function snowCanvas() { 34 /* 添加Dom结点 */ 35 var snowcanvas = document.createElement("canvas"); 36 snowcanvas.id = "snowfall"; 37 snowcanvas.width = window.innerWidth; 38 snowcanvas.height = document.body.clientHeight; 39 snowcanvas.setAttribute("style", "position:absolute; top: 0; left: 0; z-index: 1; pointer-events: none;"); 40 document.getElementsByTagName("body")[0].appendChild(snowcanvas); 41 this.canvas = snowcanvas; 42 this.ctx = snowcanvas.getContext("2d"); 43 /* 窗口大小改变的处理 */ 44 window.onresize = function() { 45 snowcanvas.width = window.innerWidth; 46 /* snowcanvas.height = window.innerHeight */ 47 } 48 } 49 /* 雪运动对象 */ 50 function flakeMove(canvasWidth, canvasHeight, flakeSize, fallSpeed) { 51 this.x = Math.floor(Math.random() * canvasWidth); /* x坐标 */ 52 this.y = Math.floor(Math.random() * canvasHeight); /* y坐标 */ 53 this.size = Math.random() * flakeSize + 2; /* 形状 */ 54 this.maxSize = flakeSize; /* 最大形状 */ 55 this.speed = Math.random() * 1 + fallSpeed; /* 坠落速度 */ 56 this.fallSpeed = fallSpeed; /* 坠落速度 */ 57 this.velY = this.speed; /* Y方向速度 */ 58 this.velX = 0; /* X方向速度 */ 59 this.stepSize = Math.random() / 30; /* 步长 */ 60 this.step = 0 /* 步数 */ 61 } 62 flakeMove.prototype.update = function() { 63 var x = this.x, 64 y = this.y; 65 /* 左右摆动(余弦) */ 66 this.velX *= 0.98; 67 if (this.velY <= this.speed) { 68 this.velY = this.speed 69 } 70 this.velX += Math.cos(this.step += .05) * this.stepSize; 71 72 this.y += this.velY; 73 this.x += this.velX; 74 /* 飞出边界的处理 */ 75 if (this.x >= canvas.width || this.x <= 0 || this.y >= canvas.height || this.y <= 0) { 76 this.reset(canvas.width, canvas.height) 77 } 78 }; 79 /* 飞出边界-放置最顶端继续坠落 */ 80 flakeMove.prototype.reset = function(width, height) { 81 this.x = Math.floor(Math.random() * width); 82 this.y = 0; 83 this.size = Math.random() * this.maxSize + 2; 84 this.speed = Math.random() * 1 + this.fallSpeed; 85 this.velY = this.speed; 86 this.velX = 0; 87 }; 88 // 渲染雪花-随机形状（此处可修改雪花颜色！！！） 89 flakeMove.prototype.render = function(ctx) { 90 var snowFlake = ctx.createRadialGradient(this.x, this.y, 0, this.x, this.y, this.size); 91 snowFlake.addColorStop(0, "rgba(255, 255, 255, 0.9)"); /* 此处是雪花颜色，默认是白色 */ 92 snowFlake.addColorStop(.5, "rgba(255, 255, 255, 0.5)"); /* 若要改为其他颜色，请自行查 */ 93 snowFlake.addColorStop(1, "rgba(255, 255, 255, 0)"); /* 找16进制的RGB 颜色代码。 */ 94 ctx.save(); 95 ctx.fillStyle = snowFlake; 96 ctx.beginPath(); 97 ctx.arc(this.x, this.y, this.size, 0, Math.PI * 2); 98 ctx.fill(); 99 ctx.restore(); 100 }; 101 /* 创建雪花-定义形状 */ 102 function createFlakes() { 103 var maxFlake = this.maxFlake, 104 flakes = this.flakes = [], 105 canvas = this.canvas; 106 for (var i = 0; i < maxFlake; i++) { 107 flakes.push(new flakeMove(canvas.width, canvas.height, this.flakeSize, this.fallSpeed)) 108 } 109 } 110 /* 画雪 */ 111 function drawSnow() { 112 var maxFlake = this.maxFlake, 113 flakes = this.flakes; 114 ctx = this.ctx, canvas = this.canvas, that = this; 115 /* 清空雪花 */ 116 ctx.clearRect(0, 0, canvas.width, canvas.height); 117 for (var e = 0; e < maxFlake; e++) { 118 flakes[e].update(); 119 flakes[e].render(ctx); 120 } 121 /* 一帧一帧的画 */ 122 this.loop = requestAnimationFrame(function() { 123 drawSnow.apply(that); 124 }); 125 } 126 /* 调用及控制方法 */ 127 var snow = new snowFall({maxFlake:60}); 128 snow.start(); 129 </script>
使用方法：
方法①、复制其中一种JS代码，粘贴到网站</body>标签之前即可；
方法②、去掉代码前后的<script **>标签，然后将代码保存为js文件，最后在网站引用即可。
Ps：若没效果，请确认网页是否已载入JQurey，如果没有请在下雪代码之前引入JQ即可。
载入jquery
1 <script type="text/javascript" src="http://libs.baidu.com/jquery/1.8.3/jquery.js"></script> 2 <script type="text/javascript" src="http://libs.baidu.com/jquery/1.8.3/jquery.min.js"></script>
注意:
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