Netlify email capture

index.js

const fetch = require("node-fetch");

const email = "foo@bar.com";

const send = () =>
  fetch("/subscribers", {
    method: "POST",
    headers: {
      "Content-Type": "application/json"
    },
    body: JSON.stringify({ email })
  })
    .then(response => response.json())
    .then(console.log)
    .catch(console.error);

Main.elm

send : Cmd Msg
send =
    Http.post
        { url = "/subscribers"
        , body =
            [ ( "email", JE.string "foo@bar.com" ) ]
                |> JE.object
                |> Http.jsonBody
        , expect = Http.expectWhatever EmailCb
        }

netlify-build-script.sh

# Add BUTTONDOWN_TOKEN to Netlify environment variables
# https://docs.netlify.com/configure-builds/file-based-configuration/#inject-environment-variable-values
npm run netlify-setup && npm run build

netlify.toml

[[redirects]]
from = "/subscribers"
to = "https://api.buttondown.email/v1/subscribers"
status = 200
headers = { Authorization = "Token TOKEN_PLACEHOLDER" }

package.json

{
  "scripts": {
    "build": "webpack",
    "netlify-setup": "sed -i s/TOKEN_PLACEHOLDER/${BUTTONDOWN_TOKEN}/g netlify.toml"
  }
}