Retrieves a value previously stored by a call to sessions.setTabValue.

You can retrieve a value from a tab even over a close/restore cycle: meaning that if you set a value, then the user closes the tab, then restores the tab using the browser's "restore tab" feature (for example, by pressing Control+Shift+T), then you will be able to retrieve the value from the restored tab. Note, though, that a restored tab does not get the same ID as the original, so the ID you pass into getTabValue() will be different from the ID you passed into setTabValue(), even though they both refer to the same tab.

This is an asynchronous function that returns a Promise.


let retrieving = browser.sessions.getTabValue(
  tabId,    // integer
  key       // string



integer. ID of the tab whose data you are trying to retrieve. Error is thrown if ID is invalid.


string. Key identifying the particular value to retrieve. This needs to match the key previously given in sessions.setTabValue.

Return value

A Promise that will be resolved with the value if it exists, or undefined if it does not exist. If the call failed (for example, because the tab ID could not be found) then the promise will be rejected with an error message.

Browser compatibility

BCD tables only load in the browser


Log the value of "my-key" for all newly created tabs (this will include any tabs that have been restored):

function onGetResolved(r) {
  console.log(`success: ${r}`);

function onGetRejected(e) {
  console.log(`error: ${e}`);

browser.tabs.onCreated.addListener((tab) => {
    .getTabValue(, "my-key")
    .then(onGetResolved, onGetRejected);

Example extensions