None.

A Promise that will be fulfilled with two arguments:

status

A runtime.RequestUpdateCheckStatus value — the result of the update check.

details Optional

object. If status is update_available, this contains more information about the update. It is an object containing a single property:

version

string. The update's version.

Request an update, and log the new version if one is available:

function onRequested(status, details) {
  console.log(status);
  if (status === "update_available") {
    console.log(details.version);
  }
}

function onError(error) {
  console.log(`Error: ${error}`);
}

let requestingCheck = browser.runtime.requestUpdateCheck(onRequested);
requestingCheck.then(onRequested, onError);