Created
December 17, 2015 20:08
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// creates a global "addWheelListener" method | |
// example: addWheelListener( elem, function( e ) { console.log( e.deltaY ); e.preventDefault(); } ); | |
(function(window,document) { | |
var prefix = "", _addEventListener, support; | |
// detect event model | |
if ( window.addEventListener ) { | |
_addEventListener = "addEventListener"; | |
} else { | |
_addEventListener = "attachEvent"; | |
prefix = "on"; | |
} | |
// detect available wheel event | |
support = "onwheel" in document.createElement("div") ? "wheel" : // Modern browsers support "wheel" | |
document.onmousewheel !== undefined ? "mousewheel" : // Webkit and IE support at least "mousewheel" | |
"DOMMouseScroll"; // let's assume that remaining browsers are older Firefox | |
window.addWheelListener = function( elem, callback, useCapture ) { | |
_addWheelListener( elem, support, callback, useCapture ); | |
// handle MozMousePixelScroll in older Firefox | |
if( support == "DOMMouseScroll" ) { | |
_addWheelListener( elem, "MozMousePixelScroll", callback, useCapture ); | |
} | |
}; | |
function _addWheelListener( elem, eventName, callback, useCapture ) { | |
elem[ _addEventListener ]( prefix + eventName, support == "wheel" ? callback : function( originalEvent ) { | |
!originalEvent && ( originalEvent = window.event ); | |
// create a normalized event object | |
var event = { | |
// keep a ref to the original event object | |
originalEvent: originalEvent, | |
target: originalEvent.target || originalEvent.srcElement, | |
type: "wheel", | |
deltaMode: originalEvent.type == "MozMousePixelScroll" ? 0 : 1, | |
deltaX: 0, | |
deltaZ: 0, | |
preventDefault: function() { | |
originalEvent.preventDefault ? | |
originalEvent.preventDefault() : | |
originalEvent.returnValue = false; | |
} | |
}; | |
// calculate deltaY (and deltaX) according to the event | |
if ( support == "mousewheel" ) { | |
event.deltaY = - 1/40 * originalEvent.wheelDelta; | |
// Webkit also support wheelDeltaX | |
originalEvent.wheelDeltaX && ( event.deltaX = - 1/40 * originalEvent.wheelDeltaX ); | |
} else { | |
event.deltaY = originalEvent.detail; | |
} | |
// it's time to fire the callback | |
return callback( event ); | |
}, useCapture || false ); | |
} | |
})(window,document); |
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