Returns true if the extension's sidebar is open in a given window.

This function accepts a windowId as a parameter:

  • If you supply windowId, the function will check the given browser window.
  • If you omit windowId, the function will check the topmost browser window.

This is an asynchronous function that returns a Promise.


let gettingIsOpen = browser.sidebarAction.isOpen(
  details // object



object. An object optionally containing the windowId to check.

windowId Optional

integer. ID of a browser window to check. If omitted defaults to windows.WINDOW_ID_CURRENT, which refers to the topmost browser window.

Return value

A Promise that will be fulfilled with true if the extension's sidebar is open in the given window, or false otherwise.

Browser compatibility

BCD tables only load in the browser


Check the topmost window:

browser.sidebarAction.isOpen({}).then((result) => {

Check all open windows:

async function checkWindow(windowId) {
  const result = await browser.sidebarAction.isOpen({ windowId });
  console.log(`window: ${windowId} status: ${result}`);
} => {
  for (const { id } of all) {