An ExtensionPanel represents a panel added to the devtools. It's the resolution of the Promise returned by browser.devtools.panels.create().


Values of this type are objects. The define two events, onShown and onHidden.

  • onShown is emitted when the panel is shown in the devtools (for example, because the user clicked on the panel's tab in the devtools window).
  • onHidden is emitted when the panel is hidden (for example, because the user switched to a different tab in the devtools window).

Browser compatibility

ChromeEdgeFirefoxFirefox for AndroidOpera
onHidden Yes No54 No Yes
onSearch Yes No No No Yes
onShown Yes No54 No Yes


This code creates a new panel, then adds handlers for its onShown and onHidden events.

function handleShown(e) {
  console.log("panel is being shown");

function handleHidden(e) {
  console.log("panel is being hidden");

  "My Panel",                 // title
  "icons/star.png",           // icon
  "devtools/panel/panel.html" // content
).then((newPanel) => {


This API is based on Chromium's chrome.devtools.panels API.

Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.

Document Tags and Contributors

Contributors to this page: hellosct1, wbamberg
Last updated by: hellosct1,