A quick guide to getting started with Google App Script.

1. Google App Script
Teach to yourself App Script in 20 minutes

2. Create New Script

3. Create a blank project

4. Write Javascript code

5. "Inbox Counter"

6. External API: JSON
https://developers.google.com/apps-script/external_apis
// Parse JSON
var json = response.getContentText();
var data = JSON.parse(json);
// Construct JSON
var data = {
"title": "Dog Skateboarding",
"description": "My dog gets some serious air"
}
var payload = JSON.stringify(data);

7. GData API

8. Simple API Usage: GmailApp
https://developers.google.com/apps-script/class_gmailapp

9. Handling GET: doGet()
function doGet(e) {
var output = ContentService.createTextOutput();
output.setMimeType(ContentService.MimeType.JSON);
output.setContent( loadData() );
return output;
}

10. Deploy

11. Deploy as web for everyone to use

12. Test URL

13. Output