There are three broad steps to getting started with the Google Analytics Realtime API.
Create a Google Analytics account for your website.
You don't need to add the provided analytics.js JavaScript snippet to your website just yet, but it'll be helpful to do so in order to work with some live data.
You'll use Google's IAM console to do this. For more instructions, see step 1 the Analytics quickstart guide. Make sure "Furnish a new private key" is checked when you create the account and that it's in JSON format. On save, you'll be prompted to download the private key. Store it securely since you Google won't ever provide another copy. Then follow the steps to add this service account to your Google Analytics account.
Add your service account's private key that you downloaded in the previous step as private_key.json in the src folder. It's important that the file be called private_key.json so that it's ignored by .gitignore. If you choose to call it something else make sure to update .gitignore to ignore the file so that you don't accidentally upload its contents to a repo somewhere.
After you've saved your private key, you can install the app's dependencies and do a dry run.
yarn install
yarn startor if you're using npm:
npm install
npm startNote that the start script will fail because ./src/index.ts sends a query to the Realtime Reporting API but it needs a profile ID in order to properly make the request. You'll set that up in the next step.
In order to query your data you'll need a profile ID. You can find this under your Analytics dashboard, under Admin, then under View Settings, in the View column.
In the final part of the main function in index.ts replace the string assigned to ids with your profile ID in the format ga:${PROFILE_ID}.
Now you can successfully query your API with
yarn startFor more on querying the API visit the Realtime Reporting API Explorer and the Realtime Reporting API Documentation