browserAction.setTitle()
Sets the browser action's title. The title is displayed in a tooltip over the browser action's icon. You can pass a tabId in or a windowId as an optional parameter — if you do this then the title is changed only for the given tab or the given window. Tabs or windows without a specific title will inherit the global title text, which defaults to the default_title or name specified in the manifest.
Syntax
js
browser.browserAction.setTitle(
  details // object
)
Parameters
details- 
    
object. The new title and optionally the ID of the tab or window to target.title- 
        
stringornull. The string the browser action should display when moused over.If
titleis an empty string, the used title will be the extension name, butbrowserAction.getTitlewill still provide the empty string.If
titleisnull:- If 
tabIdis specified, and the tab has a tab-specific title set, then the tab will inherit the title from the window to which it belongs. - if 
windowIdis specified, and the window has a window-specific title set, then the window will inherit the global title. - Otherwise, the global title will be reset to the manifest title.
 
 - If 
 tabIdOptional- 
        
integer. Sets the title only for the given tab. windowIdOptional- 
        
integer. Sets the title for the given window. 
 
- If 
windowIdandtabIdare both supplied, the function fails and the title is not set. - If 
windowIdandtabIdare both omitted, the global title is set. 
Browser compatibility
BCD tables only load in the browser
Examples
This code switches the title between "this" and "that" each time the user clicks the browser action:
js
function toggleTitle(title) {
  if (title === "this") {
    browser.browserAction.setTitle({ title: "that" });
  } else {
    browser.browserAction.setTitle({ title: "this" });
  }
}
browser.browserAction.onClicked.addListener(() => {
  let gettingTitle = browser.browserAction.getTitle({});
  gettingTitle.then(toggleTitle);
});
Example extensions
Note: This API is based on Chromium's chrome.browserAction API. This documentation is derived from browser_action.json in the Chromium code.