A jQuery plugin that adds cross-browser mouse wheel support with delta normalization.
In order to use the plugin, simply bind the mousewheel
event to an element.
It also provides two helper methods called mousewheel
and unmousewheel
that act just like other event helper methods in jQuery.
The event object is updated with the normalized deltaX
and deltaY
properties. In addition there is a new property on the event object called deltaFactor
. Multiply the deltaFactor
by deltaX
or deltaY
to get the scroll distance that the browser has reported.
Here is an example of using both the bind and helper method syntax:
// using on
$('#my_elem').on('mousewheel', function(event) {
console.log(event.deltaX, event.deltaY, event.deltaFactor);
});
// using the event helper
$('#my_elem').mousewheel(function(event) {
console.log(event.deltaX, event.deltaY, event.deltaFactor);
});
The old behavior of adding three arguments (delta
, deltaX
, and deltaY
) to the event handler is now deprecated and will be removed in later releases.
The combination of Browsers, Operating Systems, and Devices offer a huge range of possible delta values. In fact if the user uses a trackpad and then a physical mouse wheel the delta values can differ wildly. This plugin normalizes those values so you get a whole number starting at +-1 and going up in increments of +-1 according to the force or acceleration that is used. This number has the potential to be in the thousands depending on the device. Check out some of the data collected from users here.
In some use-cases we prefer to have the normalized delta but in others we want to know how far the browser should scroll based on the users input. This can be done by multiplying the deltaFactor
by the deltaX
or deltaY
event property to find the scroll distance the browser reported.
The deltaFactor
property was added to the event object in 3.1.5 so that the actual reported delta value can be extracted. This is a non-standard property.
Support for browserify is baked in.
npm install jquery-mousewheel
npm install jquery-browserify
In your server-side node.js code:
var express = require('express');
var app = express.createServer();
app.use(require('browserify')({
require : [ 'jquery-browserify', 'jquery-mousewheel' ]
}));
In your browser-side javascript:
var $ = require('jquery-browserify');
require('jquery-mousewheel')($);