"add milk to my shopping list"
Go to console.cloud.google.com and create a new project
Go to APIs & Services → Library, search Tasks API, and click Enable
Go to Credentials → Create Credentials → OAuth 2.0 Client ID, choose Web application
Under Authorized JavaScript origins add the URL where this app is hosted (e.g. https://yourdomain.com)
Copy the Client ID (ends in .apps.googleusercontent.com) and paste below