// You define this function on your page, but do not actually call it
// If present on a page it will be called by the app when the page is loaded
function median_device_info(deviceInfo) {
    console.log(deviceInfo);
}

// You may also call the median_device_info function manually, e.g. on a single page web app
median.run.deviceInfo();

// Or return the OneSignal Info via a promise (in async function)
var deviceInfo = await median.deviceInfo();

median.deviceInfo().then(function (deviceInfo) {
  console.log(deviceInfo);
});

// deviceInfo will look like
{
    platform: 'ios',
    appId: 'io.median.example',
    appVersion:  '1.0.0',
    appBuild: '1.0.0', // will be appVersionCode (number) on Android
    carrierNames: ['AT&T'], // array of all connected mobile carriers 
    distribution: 'release',
    hardware: 'armv8',
    installationId: 'xxxx-xxxx-xxxx-xxxx',
    apnsToken: '<xxxxxxxx xxxxxxxx xxxxxxxx ... >', // only on iOS
    language: 'en',
    model: 'iPhone',
    os: 'iOS',
    osVersion: '10.3',
    timeZone: 'America/New_York',
    isFirstLaunch: false // first time the app is launched
}