FxA auth dance with Daybed

index.js

function startFxAOauthDance(host, options) {
  if (host === undefined) {
    throw new Error("You should provide a host.");
  }

  if (options === undefined || options.redirect_uri === undefined) {
    throw new Error("You should provide a options.redirect_uri parameter.");
  }

  return request({
      method: "POST",
      host: host,
      body: {redirect_uri: options.redirect_uri},
      url: "/tokens/fxa-oauth/params"
    }).then(function(doc) {
      document.location.href = doc.oauth_uri + "/authorization?" + \
        "client_id=" + doc.client_id + \
        "&state=" + doc.state + \
        "&scope=profile&action=signin";
    });
}