How can I access the contents of a (new-style) Google sheet a JSON? My aim is to access the values from JavaScript, so I need to be able to download the JSON via HTTP.
A faster solution here is to use this https://gist.github.com/ronaldsmartin/47f5239ab1834c47088e to wrap around your existing spreadsheet.
You first need to change your sheet access to Anyone with link can View
Add the id and sheet html param to the URL below.
https://script.google.com/macros/s/AKfycbzGvKKUIaqsMuCj7-A2YRhR-f7GZjl4kSxSN1YyLkS01_CfiyE/exec
Eg: your id is your sheet id which is
1mhv1lpzufTruZhzrY-ms0ciDVKYiFJLWCMpi4OOuqvI
and your sheet which is
Sheet2
In your case you can actually see your data here as json at
https://script.google.com/macros/s/AKfycbzGvKKUIaqsMuCj7-A2YRhR-f7GZjl4kSxSN1YyLkS01_CfiyE/exec?id=1mhv1lpzufTruZhzrY-ms0ciDVKYiFJLWCMpi4OOuqvI&sheet=Sheet2
To be safe, you should deploy the code sheetAsJson.gs in the github gist above as your own in your Google Drive.