Function shouldAdjustOldDeltas

jquery.mousewheel.js:229–240

( orgEvent, absDelta )

    }

    function shouldAdjustOldDeltas( orgEvent, absDelta ) {

        // If this is an older event and the delta is divisible 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;
    }

} );