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

Update compatibility data on GitHub
ChromeEdgeFirefoxOperaSafariFirefox for Android
isOpenChrome No support NoEdge No support NoFirefox Full support 59Opera No support NoSafari No support NoFirefox Android No support No


Full support  
Full support
No support  
No support


Check the topmost window:

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

  Check all open windows:

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