又到了年底，从圣诞节开始，可以发现各大网站的活动是越来越多，都变的银装素裹，本人由于业务需求也需要做这么一个效果，所以就通过google大神找了一下相关资源，结果就出现了N种雪花效果的方式。种类繁多，最后找到了本文看到的这种效果，原作者写的可以说已经满足了我的需求，但是为了符合更多的场景，又再原作者的基础上做了调整。
声明：本文核心代码归原作者@Ivan Lazarevic（https://github.com/kopipejst）所有，本人只增加了一些参数和效果
兼容性：除IE外各主流浏览器（当然也可以调整代码，支持IE高版本浏览器，本文实例不支持IE）
经过调整的代码如下：
（上半部分为jquery-easing，下半部分为雪花效果）
(function($){
/*
* jQuery Easing v1.3 - http://gsgd.co.uk/sandbox/jquery/easing/
*
* Uses the built in easing capabilities added In jQuery 1.1
* to offer multiple easing options
*
* TERMS OF USE - jQuery Easing
*
* Open source under the BSD License.
*
* Copyright © 2008 George McGinley Smith
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list
* of conditions and the following disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* Neither the name of the author nor the names of contributors may be used to endorse
* or promote products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
// t: current time, b: begInnIng value, c: change In value, d: duration
jQuery.easing['jswing'] = jQuery.easing['swing'];
jQuery.extend( jQuery.easing,
{
def: 'easeOutQuad',
swing: function (x, t, b, c, d) {
//alert(jQuery.easing.default);
return jQuery.easing[jQuery.easing.def](x, t, b, c, d);
},
easeInQuad: function (x, t, b, c, d) {
return c*(t/=d)*t + b;
},
easeOutQuad: function (x, t, b, c, d) {
return -c *(t/=d)*(t-2) + b;
},
easeInOutQuad: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return c/2*t*t + b;
return -c/2 * ((--t)*(t-2) - 1) + b;
},
easeInCubic: function (x, t, b, c, d) {
return c*(t/=d)*t*t + b;
},
easeOutCubic: function (x, t, b, c, d) {
return c*((t=t/d-1)*t*t + 1) + b;
},
easeInOutCubic: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return c/2*t*t*t + b;
return c/2*((t-=2)*t*t + 2) + b;
},
easeInQuart: function (x, t, b, c, d) {
return c*(t/=d)*t*t*t + b;
},
easeOutQuart: function (x, t, b, c, d) {
return -c * ((t=t/d-1)*t*t*t - 1) + b;
},
easeInOutQuart: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return c/2*t*t*t*t + b;
return -c/2 * ((t-=2)*t*t*t - 2) + b;
},
easeInQuint: function (x, t, b, c, d) {
return c*(t/=d)*t*t*t*t + b;
},
easeOutQuint: function (x, t, b, c, d) {
return c*((t=t/d-1)*t*t*t*t + 1) + b;
},
easeInOutQuint: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return c/2*t*t*t*t*t + b;
return c/2*((t-=2)*t*t*t*t + 2) + b;
},
easeInSine: function (x, t, b, c, d) {
return -c * Math.cos(t/d * (Math.PI/2)) + c + b;
},
easeOutSine: function (x, t, b, c, d) {
return c * Math.sin(t/d * (Math.PI/2)) + b;
},
easeInOutSine: function (x, t, b, c, d) {
return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
},
easeInExpo: function (x, t, b, c, d) {
return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b;
},
easeOutExpo: function (x, t, b, c, d) {
return (t==d) ? b+c : c * (-Math.pow(2, -10 * t/d) + 1) + b;
},
easeInOutExpo: function (x, t, b, c, d) {
if (t==0) return b;
if (t==d) return b+c;
if ((t/=d/2) < 1) return c/2 * Math.pow(2, 10 * (t - 1)) + b;
return c/2 * (-Math.pow(2, -10 * --t) + 2) + b;
},
easeInCirc: function (x, t, b, c, d) {
return -c * (Math.sqrt(1 - (t/=d)*t) - 1) + b;
},
easeOutCirc: function (x, t, b, c, d) {
return c * Math.sqrt(1 - (t=t/d-1)*t) + b;
},
easeInOutCirc: function (x, t, b, c, d) {
if ((t/=d/2) < 1) return -c/2 * (Math.sqrt(1 - t*t) - 1) + b;
return c/2 * (Math.sqrt(1 - (t-=2)*t) + 1) + b;
},
easeInElastic: function (x, t, b, c, d) {
var s=1.70158;var p=0;var a=c;
if (t==0) return b; if ((t/=d)==1) return b+c; if (!p) p=d*.3;
if (a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
},
easeOutElastic: function (x, t, b, c, d) {
var s=1.70158;var p=0;var a=c;
if (t==0) return b; if ((t/=d)==1) return b+c; if (!p) p=d*.3;
if (a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
},
easeInOutElastic: function (x, t, b, c, d) {
var s=1.70158;var p=0;var a=c;
if (t==0) return b; if ((t/=d/2)==2) return b+c; if (!p) p=d*(.3*1.5);
if (a < Math.abs(c)) { a=c; var s=p/4; }
else var s = p/(2*Math.PI) * Math.asin (c/a);
if (t < 1) return -.5*(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
return a*Math.pow(2,-10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )*.5 + c + b;
},
easeInBack: function (x, t, b, c, d, s) {
if (s == undefined) s = 1.70158;
return c*(t/=d)*t*((s+1)*t - s) + b;
},
easeOutBack: function (x, t, b, c, d, s) {
if (s == undefined) s = 1.70158;
return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
},
easeInOutBack: function (x, t, b, c, d, s) {
if (s == undefined) s = 1.70158;
if ((t/=d/2) < 1) return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
},
easeInBounce: function (x, t, b, c, d) {
return c - jQuery.easing.easeOutBounce (x, d-t, 0, c, d) + b;
},
easeOutBounce: function (x, t, b, c, d) {
if ((t/=d) < (1/2.75)) {
return c*(7.5625*t*t) + b;
} else if (t < (2/2.75)) {
return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b;
} else if (t < (2.5/2.75)) {
return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b;
} else {
return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b;
}
},
easeInOutBounce: function (x, t, b, c, d) {
if (t < d/2) return jQuery.easing.easeInBounce (x, t*2, 0, c, d) * .5 + b;
return jQuery.easing.easeOutBounce (x, t*2-d, 0, c, d) * .5 + c*.5 + b;
}
});
/*
*
* TERMS OF USE - EASING EQUATIONS
*
* Open source under the BSD License.
*
* Copyright © 2001 Robert Penner
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list
* of conditions and the following disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* Neither the name of the author nor the names of contributors may be used to endorse
* or promote products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
$.fn.snow = function(options){
//处理浏览器
var na = window.navigator;
var ua = na.userAgent.toLowerCase();
var browserTester = /(webkit|gecko|presto|opera|safari|firefox|chrome|applewebkit)[ /os]*([d_.]+)/ig
if(!browserTester.test(ua)) {
return;
}
var winHeight = $(window).height();
var docHeight = $(document).height();
var docWidth = $(document).width();
var defaults = {
minSize: 20, //雪花的最小尺寸
maxSize: 50, //雪花的最大尺寸
speed: docHeight * 10, //雪花掉落速度
frequency: 500, //雪花出现的频率
color: "#FFFFFF", //雪花颜色
easing: 'linear', //雪花动画效果
position: 'absolute' //定位方式
};
var options = $.extend({}, defaults, options);
var $snow = $('<div>').css({'position': options.position, 'top': '-50px', 'z-index':9999999999}).html('❄');
var height = options.position == "fixed" ? winHeight : docHeight;
var width = docWidth;
$('body').css('overflow-x', 'hidden');
var interval = setInterval( function(){
var startPositionLeft = Math.random() * width - 100;
var startOpacity = 0.5 + Math.random();
var size = options.minSize + Math.random() * options.maxSize;
var endPositionTop = height - 40;
var endPositionLeft = startPositionLeft + (Math.random()*10 > 5 ? -500 : 500);
$snow.clone().appendTo('body').css({
left: startPositionLeft,
opacity: startOpacity,
'font-size': size,
color: options.color
}).animate({
top: endPositionTop,
left: endPositionLeft,
opacity: 0.2
},options.speed, options.easing,function(){
$(this).remove()
}
);
}, options.frequency);
};
})(jQuery);
调整点有：
- 增加speed参数，指的是每个雪花的生命周期时长
- 增加frequency参数，指的是每个雪花之间的间隔时长
- 增加easing参数，支持jquery-easing插件的所有动画，定义每个雪花的动画
- 增加position参数，支持雪花随屏幕下落
JS线上地址：http://s7.qhimg.com/!88157db8/jquery-plugin-snow.js
另附带一个直接引用JS就可以的资源：http://s5.qhimg.com/static/5ebcf40d746a2dc0/snow/snow.src.js （canvas版本）
参考资料：
http://gsgd.co.uk/sandbox/jquery/easing/ （动画效果使用easing）