runtime.getPlatformInfo()

Returns information about the current platform. This can only be called in the background script context.

This is an asynchronous function that returns a Promise.

None.

A Promise that will be fulfilled with a runtime.PlatformInfo value representing the current platform.

Get and log the platform OS:

function gotPlatformInfo(info) {
  console.log(info.os);
}

let gettingInfo = browser.runtime.getPlatformInfo();
gettingInfo.then(gotPlatformInfo);