【jquery外掛程式】-網頁下雪效果

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    又到了年底，從聖誕節開始，可以發現各大網站的活動是越來越多，都變的銀裝素裹，本人由於業務需求也需要做這麼一個效果，所以就通過google大神找了一下相關資源，結果就出現了N種雪花效果的方式。種類繁多，最後找到了本文看到的這種效果，原作者寫的可以說已經滿足了我的需求，但是為了符合更多的情境，又再原作者的基礎上做了調整。     聲明：本文核心代碼歸原作者@Ivan Lazarevic（https://github.com/kopipejst）所有，本人只增加了一些參數和效果     相容性：除IE外各主流瀏覽器（當然也可以調整代碼，支援IE高版本瀏覽器，本文執行個體不支援IE）     經過調整的代碼如下：    （上半部分為jquery-easing，下半部分為雪花效果）      

(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: durationjQuery.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){//處理瀏覽器var na = window.navigator;var ua = na.userAgent.toLowerCase();var browserTester = /(webkit|gecko|presto|opera|safari|firefox|chrome|applewebkit)[ \/os]*([\d_.]+)/igif(!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,//雪花出現的頻率color: "#FFFFFF", //雪花顏色easing: ‘linear‘, //雪花動畫效果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);

     調整點有：

• 增加speed參數，指的是每個雪花的生命週期時間長度
• 增加frequency參數，指的是每個雪花之間的間隔時間長度
• 增加easing參數，支援jquery-easing外掛程式的所有動畫，定義每個雪花的動畫
• 增加position參數，支援雪花隨螢幕下落

 JS線上地址：http://s7.qhimg.com/!88157db8/jquery-plugin-snow.js 效果展示 參考資料：http://workshop.rs/2012/01/jquery-snow-falling-plugin/（原作者地址，稍作調整）http://gsgd.co.uk/sandbox/jquery/easing/ （動畫效果使用easing）

【jquery外掛程式】-網頁下雪效果