src/basis/dom/event.js
function wheelDelta(event){
    var delta = 0;

    if ('deltaY' in event)
      delta = -event.deltaY;      // safari & gecko
    else
      if ('wheelDelta' in event)
        delta = event.wheelDelta; // IE, webkit, opera
      else
        if (event.type == 'DOMMouseScroll')
          delta = -event.detail;  // old gecko

    return delta && (delta / Math.abs(delta));
  }
function wheelDelta(event){
    var delta = 0;

    if ('deltaY' in event)
      delta = -event.deltaY;      // safari & gecko
    else
      if ('wheelDelta' in event)
        delta = event.wheelDelta; // IE, webkit, opera
      else
        if (event.type == 'DOMMouseScroll')
          delta = -event.detail;  // old gecko

    return delta && (delta / Math.abs(delta));
  }
function wheelDelta ( event ) { var delta = 0 ; if ( 'deltaY' in event ) delta = - event . deltaY ; // safari & gecko else if ( 'wheelDelta' in event ) delta = event . wheelDelta ; // IE, webkit, opera else if ( event . type == 'DOMMouseScroll' ) delta = - event . detail ; // old gecko return delta && ( delta / Math . abs ( delta ) ) ; }
Returns mouse wheel delta.
@param {Event} event
@return {number} -1, 0, 1
Returns mouse wheel delta .