Function wheelEventDelta

static/editor.md/lib/codemirror/lib/codemirror.js:3826–3832

(e)

  else if (safari) wheelPixelsPerUnit = -1/3;

  var wheelEventDelta = function(e) {
    var dx = e.wheelDeltaX, dy = e.wheelDeltaY;
    if (dx == null && e.detail && e.axis == e.HORIZONTAL_AXIS) dx = e.detail;
    if (dy == null && e.detail && e.axis == e.VERTICAL_AXIS) dy = e.detail;
    else if (dy == null) dy = e.wheelDelta;
    return {x: dx, y: dy};
  };
  CodeMirror.wheelEventPixels = function(e) {
    var delta = wheelEventDelta(e);
    delta.x *= wheelPixelsPerUnit;