Get POST data submitted as either JSON or FormData

getPostData.js

export async function getPostData(request) {
  const {headers} = request;
  const contentType = headers.get("content-type") || "";
  
  if (contentType.includes("application/json")) {
    return await request.json();
  }

  if (contentType.includes("form")) {
    const formData = await request.formData();
    const body = {};

    for (const entry of formData.entries()) {
      body[entry[0]] = entry[1];
    }

    return body
  }

  return undefined;
}