现在的网页设计越来越高大上，效果越来越炫酷毙。一些浏览器的默认东西都被纷纷嫌弃，取而代之的是各种酷炫拽的模拟组件。就好像之前说过的视差滚动，又好像各种小清新的模拟滚动条，都有共同的事件：滚轮事件。
正如大家所知道的那样，jquery框架默认是不支持鼠标中轮滚轮事件的。要实现不同浏览器之间的滚轮事件，我们不能不说一下这个js组件了：jquery.mousewheel.js。
什么都不说，先上源码：
/*! Copyright (c) 2013 Brandon Aaron (http://brandon.aaron.sh)
* Licensed under the MIT License (LICENSE.txt).
*
* Version: 3.1.11
*
* Requires: jQuery 1.2.2+
*/
(function (factory) {
if ( typeof define === 'function' && define.amd ) {
// AMD. Register as an anonymous module.
define(['jquery'], factory);
} else if (typeof exports === 'object') {
// Node/CommonJS style for Browserify
module.exports = factory;
} else {
// Browser globals
factory(jQuery);
}
}(function ($) {
var toFix = ['wheel', 'mousewheel', 'DOMMouseScroll', 'MozMousePixelScroll'],
toBind = ( 'onwheel' in document || document.documentMode >= 9 ) ?
['wheel'] : ['mousewheel', 'DomMouseScroll', 'MozMousePixelScroll'],
slice = Array.prototype.slice,
nullLowestDeltaTimeout, lowestDelta;
if ( $.event.fixHooks ) {
for ( var i = toFix.length; i; ) {
$.event.fixHooks[ toFix[--i] ] = $.event.mouseHooks;
}
}
var special = $.event.special.mousewheel = {
version: '3.1.11',
setup: function() {
if ( this.addEventListener ) {
for ( var i = toBind.length; i; ) {
this.addEventListener( toBind[--i], handler, false );
}
} else {
this.onmousewheel = handler;
}
// Store the line height and page height for this particular element
$.data(this, 'mousewheel-line-height', special.getLineHeight(this));
$.data(this, 'mousewheel-page-height', special.getPageHeight(this));
},
teardown: function() {
if ( this.removeEventListener ) {
for ( var i = toBind.length; i; ) {
this.removeEventListener( toBind[--i], handler, false );
}
} else {
this.onmousewheel = null;
}
// Clean up the data we added to the element
$.removeData(this, 'mousewheel-line-height');
$.removeData(this, 'mousewheel-page-height');
},
getLineHeight: function(elem) {
var $parent = $(elem)['offsetParent' in $.fn ? 'offsetParent' : 'parent']();
if (!$parent.length) {
$parent = $('body');
}
return parseInt($parent.css('fontSize'), 10);
},
getPageHeight: function(elem) {
return $(elem).height();
},
settings: {
adjustOldDeltas: true, // see shouldAdjustOldDeltas() below
normalizeOffset: true // calls getBoundingClientRect for each event
}
};
$.fn.extend({
mousewheel: function(fn) {
return fn ? this.bind('mousewheel', fn) : this.trigger('mousewheel');
},
unmousewheel: function(fn) {
return this.unbind('mousewheel', fn);
}
});
function handler(event) {
var orgEvent = event || window.event,
args = slice.call(arguments, 1),
delta = 0,
deltaX = 0,
deltaY = 0,
absDelta = 0,
offsetX = 0,
offsetY = 0;
event = $.event.fix(orgEvent);
event.type = 'mousewheel';
// Old school scrollwheel delta
if ( 'detail' in orgEvent ) { deltaY = orgEvent.detail * -1; }
if ( 'wheelDelta' in orgEvent ) { deltaY = orgEvent.wheelDelta; }
if ( 'wheelDeltaY' in orgEvent ) { deltaY = orgEvent.wheelDeltaY; }
if ( 'wheelDeltaX' in orgEvent ) { deltaX = orgEvent.wheelDeltaX * -1; }
// Firefox < 17 horizontal scrolling related to DOMMouseScroll event
if ( 'axis' in orgEvent && orgEvent.axis === orgEvent.HORIZONTAL_AXIS ) {
deltaX = deltaY * -1;
deltaY = 0;
}
// Set delta to be deltaY or deltaX if deltaY is 0 for backwards compatabilitiy
delta = deltaY === 0 ? deltaX : deltaY;
// New school wheel delta (wheel event)
if ( 'deltaY' in orgEvent ) {
deltaY = orgEvent.deltaY * -1;
delta = deltaY;
}
if ( 'deltaX' in orgEvent ) {
deltaX = orgEvent.deltaX;
if ( deltaY === 0 ) { delta = deltaX * -1; }
}
// No change actually happened, no reason to go any further
if ( deltaY === 0 && deltaX === 0 ) { return; }
// Need to convert lines and pages to pixels if we aren't already in pixels
// There are three delta modes:
// * deltaMode 0 is by pixels, nothing to do
// * deltaMode 1 is by lines
// * deltaMode 2 is by pages
if ( orgEvent.deltaMode === 1 ) {
var lineHeight = $.data(this, 'mousewheel-line-height');
delta *= lineHeight;
deltaY *= lineHeight;
deltaX *= lineHeight;
} else if ( orgEvent.deltaMode === 2 ) {
var pageHeight = $.data(this, 'mousewheel-page-height');
delta *= pageHeight;
deltaY *= pageHeight;
deltaX *= pageHeight;
}
// Store lowest absolute delta to normalize the delta values
absDelta = Math.max( Math.abs(deltaY), Math.abs(deltaX) );
if ( !lowestDelta || absDelta < lowestDelta ) {
lowestDelta = absDelta;
// Adjust older deltas if necessary
if ( shouldAdjustOldDeltas(orgEvent, absDelta) ) {
lowestDelta /= 40;
}
}
// Adjust older deltas if necessary
if ( shouldAdjustOldDeltas(orgEvent, absDelta) ) {
// Divide all the things by 40!
delta /= 40;
deltaX /= 40;
deltaY /= 40;
}
// Get a whole, normalized value for the deltas
delta = Math[ delta >= 1 ? 'floor' : 'ceil' ](delta / lowestDelta);
deltaX = Math[ deltaX >= 1 ? 'floor' : 'ceil' ](deltaX / lowestDelta);
deltaY = Math[ deltaY >= 1 ? 'floor' : 'ceil' ](deltaY / lowestDelta);
// Normalise offsetX and offsetY properties
if ( special.settings.normalizeOffset && this.getBoundingClientRect ) {
var boundingRect = this.getBoundingClientRect();
offsetX = event.clientX - boundingRect.left;
offsetY = event.clientY - boundingRect.top;
}
// Add information to the event object
event.deltaX = deltaX;
event.deltaY = deltaY;
event.deltaFactor = lowestDelta;
event.offsetX = offsetX;
event.offsetY = offsetY;
// Go ahead and set deltaMode to 0 since we converted to pixels
// Although this is a little odd since we overwrite the deltaX/Y
// properties with normalized deltas.
event.deltaMode = 0;
// Add event and delta to the front of the arguments
args.unshift(event, delta, deltaX, deltaY);
// Clearout lowestDelta after sometime to better
// handle multiple device types that give different
// a different lowestDelta
// Ex: trackpad = 3 and mouse wheel = 120
if (nullLowestDeltaTimeout) { clearTimeout(nullLowestDeltaTimeout); }
nullLowestDeltaTimeout = setTimeout(nullLowestDelta, 200);
return ($.event.dispatch || $.event.handle).apply(this, args);
}
function nullLowestDelta() {
lowestDelta = null;
}
function shouldAdjustOldDeltas(orgEvent, absDelta) {
// If this is an older event and the delta is divisable by 120,
// then we are assuming that the browser is treating this as an
// older mouse wheel event and that we should divide the deltas
// by 40 to try and get a more usable deltaFactor.
// Side note, this actually impacts the reported scroll distance
// in older browsers and can cause scrolling to be slower than native.
// Turn this off by setting $.event.special.mousewheel.settings.adjustOldDeltas to false.
return special.settings.adjustOldDeltas && orgEvent.type === 'mousewheel' && absDelta % 120 === 0;
}
}));
js插件里面主要的2个函数就是mousewheel和unmousewheel。
调用方式也是多种多样，
例如你可以这样：
$('.demo').mousewheel(function(){
//to do something
});
$('.demo').bind('mousewheel', function(){
//to do something
});
下面来说说它的参数。
mousewheel事件的参数除了第一个参数event外，还会接收第二个参数delta。通过参数delta可以获取鼠标滚轮的方向和速度。如果delta的值是负的，那么滚轮就是向下滚动，正的就是向上。
举个例子：
var gao=document.documentElement.clientHeight,h,wflag=true,fh=0,uph=0,yundong=true;
$('.mod-step').css('height',gao);
$('.mod-step').bind('mousewheel', function(event, delta) {
if(yundong==true){
yundong=false;
var index=parseInt($(this).index('.mod-step'))+1;
h=gao*index;
if(delta < 0){ //如果是向下滚动就干什么事情
//to do something
}else{ //如果是向上滚动就干什么事情
//to do something
}
ps:看看参数如何调用就行,其他代码的细节可以忽略。
接下来看看不同浏览器返回的不同的值。
先看谷歌浏览器的：向下滚动时，
然后是火狐的，向下滚动时，
然后是ie11的，向下滚动：
然后是ie9的，向下滚动：
接下来就是ie8，向下滚动的：
总结：各种浏览器返回的数值基本都不一样。所以如果要用具体数字判断，还是不科学的，但是用是否大于0，还是靠谱的。
当中的差异，如果有兴趣的可以去张鑫旭的博客看看。附上网址：http://www.zhangxinxu.com/wordpress/2013/04/js-mousewheel-dommousescroll-event/
滚轮事件的各种运用，我就不多说了，提供几个demo给大家去看看，真心好用。
http://manos.malihu.gr/jquery-custom-content-scroller/
http://noraesae.github.io/perfect-scrollbar/
总结：虽然不是什么大插件，但是填补了jQuery没有滚轮事件的缺陷，简单实用。
Author: Alone
Antroduction: 高级前端开发工程师
Sign: 人生没有失败，只有没到的成功。
时间： 2024-08-14 09:45:16