<script type="text/javascript">
(function($){
$.fn.snow = function(options){
var $flake = $('<div id="snowbox" />').css({'position': 'absolute','z-index':'9999', 'top': '-50px'}).html('❄'),
documentHeight = $(document).height(),
documentWidth = $(document).width(),
defaults = {
minSize : 10,
maxSize : 20,
newOn : 1000,
flakeColor : "#AFDAEF" /* 此处可以定义雪花颜色，若要白色可以改为#FFFFFF */
},
options = $.extend({}, defaults, options);
var interval= setInterval( function(){
var startPositionLeft = Math.random() * documentWidth - 100,
startOpacity = 0.5 + Math.random(),
sizeFlake = options.minSize + Math.random() * options.maxSize,
endPositionTop = documentHeight - 200,
endPositionLeft = startPositionLeft - 500 + Math.random() * 500,
durationFall = documentHeight * 10 + Math.random() * 5000;
$flake.clone().appendTo('body').css({
left: startPositionLeft,
opacity: startOpacity,
'font-size': sizeFlake,
color: options.flakeColor
}).animate({
top: endPositionTop,
left: endPositionLeft,
opacity: 0.2
},durationFall,'linear',function(){
$(this).remove()
});
}, options.newOn);
};
})(jQuery);
$(function(){
$.fn.snow({
minSize: 5, /* 定义雪花最小尺寸 */
maxSize: 50,/* 定义雪花最大尺寸 */
newOn: 300 /* 定义密集程度，数字越小越密集 */
});
});
</script>
源码来源：https://gitee.com/wmc1125/codes/mxu0f9o1t4vyc62w5eibq33