devtools.inspectedWindow.tabId

The ID of the tab that this instance of the devtools is attached to, represented as a number.

This can be sent to the extension's background page, so that background page can use the tabs API to interact with the tab:

// devtools-panel.js

const scriptToAttach = "document.body.innerHTML = 'Hi from the devtools';";

attachContentScriptButton.addEventListener("click", () => {
  browser.runtime.sendMessage({
    tabId: browser.devtools.inspectedWindow.tabId,
    script: scriptToAttach
  });
});

// background.js

function handleMessage(request, sender, sendResponse) {
  browser.tabs.executeScript(request.tabId, {
    code: request.script
  });
}

browser.runtime.onMessage.addListener(handleMessage);

Browser compatibility

BCD tables only load in the browser

Acknowledgements

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

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