SvelteKit でアプリ内フィードバックフォームを作る

src/
  app.d.ts
  env.ts
  hooks.server.ts
  lib/
    FeedbackForm.svelte
    server/session.ts
  routes/
    (app)/+layout.svelte
    feedback/
      +page.server.ts
      +page.svelte
.env

IKIFORM_SECRET_KEY=ik_sk_your_secret_key

import { defineEnvVars } from "@sveltejs/kit/env";

export const variables = defineEnvVars({
  IKIFORM_SECRET_KEY: {},
});

declare global {
  namespace App {
    interface Locals {
      user: { id: string; email: string } | null;
    }
  }
}

export {};

import type { Handle } from "@sveltejs/kit/hooks";
import { readSession } from "#lib/server/session.js";

export const handle: Handle = async ({ event, resolve }) => {
  event.locals.user = await readSession(event.cookies.get("session"));
  return resolve(event);
};

import { fail } from "@sveltejs/kit";
import { IKIFORM_SECRET_KEY } from "$app/env/private";
import type { Actions } from "./$types";

export const prerender = false;

const SCREEN = /^[a-z0-9/[\]._-]{1,120}$/;

function pageFrom(referer: string | null, origin: string) {
  try {
    const url = new URL(referer ?? "");
    return url.origin === origin ? url.origin + url.pathname : "";
  } catch {
    return "";
  }
}

export const actions = {
  send: async ({ request, locals, url }) => {
    const data = await request.formData();
    if (!locals.user) return fail(401, { message: "Your session ended. Sign in again, then send it." });

    const rating = Number(data.get("rating"));
    if (!Number.isInteger(rating) || rating < 1 || rating > 5) {
      return fail(400, { message: "Pick a score from 1 to 5." });
    }

    const screen = String(data.get("screen") ?? "").replace(/\/\([^)]+\)/g, "") || "/";
    const back = pageFrom(request.headers.get("referer"), url.origin);

    let response: Response;
    try {
      response = await fetch("https://ikiform.com/f/frm_xxxxxxxxxxxxxxxx", {
        method: "POST",
        headers: {
          Accept: "application/json",
          "Content-Type": "application/json",
          Authorization: `Bearer ${IKIFORM_SECRET_KEY}`,
          Origin: request.headers.get("origin") ?? url.origin,
        },
        body: JSON.stringify({
          rating,
          comment: String(data.get("comment") ?? "").trim().slice(0, 4000),
          page: back,
          screen: SCREEN.test(screen) ? screen : "unknown",
          user_id: locals.user.id,
          email: locals.user.email,
          _gotcha: String(data.get("_gotcha") ?? ""),
        }),
        signal: AbortSignal.timeout(8000),
      });
    } catch {
      return fail(502, { message: "We couldn't send it. Try again in a moment." });
    }

    if (response.status === 429) return fail(429, { message: "Too many answers at once. Try again in a minute." });
    const result = await response.json().catch(() => null);
    if (!result?.ok) {
      return fail(400, { message: result?.error?.fields?.comment?.[0] ?? result?.error?.message ?? "We couldn't send it." });
    }
    return { sent: true, back };
  },
} satisfies Actions;

<script lang="ts">
  import { enhance } from "$app/forms";
  import { page } from "$app/state";

  const scores = ["Broken", "Frustrating", "Fine", "Good", "Great"];
  let sending = $state(false);
</script>

{#if page.form?.sent}
  <p role="status">Thanks. We read every one.</p>
{:else}
  <form
    method="POST"
    action="/feedback?/send"
    aria-busy={sending}
    use:enhance={() => {
      sending = true;
      return async ({ update }) => {
        await update({ navigate: false, refreshAll: false });
        sending = false;
      };
    }}
  >
    <fieldset>
      <legend>How is this screen working for you?</legend>
      {#each scores as label, index}
        <label><input type="radio" name="rating" value={index + 1} required /> {label}</label>
      {/each}
    </fieldset>
    <label for="feedback-comment">What would make it better?</label>
    <textarea id="feedback-comment" name="comment" rows="4" maxlength="4000"></textarea>
    <input type="hidden" name="screen" value={page.route.id ?? ""} />
    <input name="_gotcha" type="text" tabindex="-1" autocomplete="off" hidden />
    {#if page.form?.message}
      <p role="alert">{page.form.message}</p>
    {/if}
    <button disabled={sending}>{sending ? "Sending" : "Send feedback"}</button>
  </form>
{/if}

<script lang="ts">
  import FeedbackForm from "#lib/FeedbackForm.svelte";

  let { children } = $props();
</script>

<main>{@render children()}</main>
<aside>
  <FeedbackForm />
</aside>

<script lang="ts">
  import type { PageProps } from "./$types";

  let { form }: PageProps = $props();
</script>

{#if form?.sent}
  <p role="status">Thanks. We read every one.</p>
  <a href={form.back || "/"}>Back to where you were</a>
{:else if form?.message}
  <p role="alert">{form.message}</p>
  <a href="/">Back to the app</a>
{:else}
  <p>Send feedback from the panel on any screen of the app.</p>
{/if}