This topic provides sample code that shows how to return an output in JSON format.

Sample code

async function handler(event) {
  const data = {
    hello: "EdgeRoutine"
     }
  const json = JSON.stringify(data, null, 2)
  return new Response(json, {
      headers: {
        "content-type": "application/json;charset=UTF-8"
      }
    })
}

addEventListener('fetch', (event) => {
    event.respondWith(handler(event));
});

Result

An output in JSON format