function getButton()

in src/Terminal.ts [948:1008]

• 43 lines of code
• 20 McCabe index (conditional complexity)

    function getButton(ev: MouseEvent): number {
      let button;
      let shift;
      let meta;
      let ctrl;
      let mod;

      // two low bits:
      // 0 = left
      // 1 = middle
      // 2 = right
      // 3 = release
      // wheel up/down:
      // 1, and 2 - with 64 added
      switch ((<any>ev).overrideType || ev.type) {
        case 'mousedown':
          button = ev.button !== null && ev.button !== undefined
            ? +ev.button
          : ev.which !== null && ev.which !== undefined
            ? ev.which - 1
          : null;

          if (Browser.isMSIE) {
            button = button === 1 ? 0 : button === 4 ? 1 : button;
          }
          break;
        case 'mouseup':
          button = 3;
          break;
        case 'DOMMouseScroll':
          button = ev.detail < 0
            ? 64
          : 65;
          break;
        case 'wheel':
          button = (<WheelEvent>ev).wheelDeltaY > 0
            ? 64
          : 65;
          break;
      }

      // next three bits are the modifiers:
      // 4 = shift, 8 = meta, 16 = control
      shift = ev.shiftKey ? 4 : 0;
      meta = ev.metaKey ? 8 : 0;
      ctrl = ev.ctrlKey ? 16 : 0;
      mod = shift | meta | ctrl;

      // no mods
      if (self.vt200Mouse) {
        // ctrl only
        mod &= ctrl;
      } else if (!self.normalMouse) {
        mod = 0;
      }

      // increment to SP
      button = (32 + (mod << 2)) + button;

      return button;
    }