post fetch rails json with csrf token

post fetch rails json with csrf token.coffee

post = (url, body) ->
  token = document.querySelector('meta[name="csrf-token"]').attributes.content.value

  fetch("#{url}.json",
    method: "POST"
    mode: "cors"
    cache: "no-cache"
    credentials: "same-origin"
    headers:
      "Content-Type": "application/json"
      "X-CSRF-Token": token
    redirect: "follow"
    referrer: "no-referrer"
    body: body
  ).then (response) -> response.json()