Function nextFrame

background_scripts/main.js:367–400

({ count, tabId })

  },

  async nextFrame({ count, tabId }) {
    // We're assuming that these frames are returned in the order that they appear on the page. This
    // seems to be the case empirically. If it's ever needed, we could also sort by frameId.
    let frameIds = await getFrameIdsForTab(tabId);
    const promises = frameIds.map(async (frameId) => {
      // It is possible that this sendMessage call fails, if a frame gets unloaded while the request
      // is in flight.
      let isError = false;
      const status = await (chrome.tabs.sendMessage(tabId, { handler: "getFocusStatus" }, {
        frameId: frameId,
      }).catch((_) => {
        isError = true;
      }));
      return { frameId, status, isError };
    });

    const frameResponses = (await Promise.all(promises)).filter((r) => !r.isError);

    const focusedFrameId = frameResponses.find(({ status }) => status.focused)?.frameId;
    // It's theoretically possible that focusedFrameId is null if the user switched tabs or away
    // from the browser while the request is in flight.
    if (focusedFrameId == null) return;

    // Prune any frames which gave an error response (i.e. they disappeared).
    frameIds = frameResponses.filter((r) => r.status.focusable).map((r) => r.frameId);

    const index = frameIds.indexOf(focusedFrameId);
    count = count ?? 1;
    const nextIndex = (index + count) % frameIds.length;
    if (index == nextIndex) return;
    await chrome.tabs.sendMessage(tabId, { handler: "focusFrame", highlight: true }, {
      frameId: frameIds[nextIndex],
    });
  },

  async closeTabsOnLeft(request) {
    await removeTabsRelative("before", request);