fix(router): properly parse json response in the FormAction

apps/analog-app-e2e-cypress/src/e2e/newsletter.cy.ts

@@ -0,0 +1,16 @@
+import * as newsletter from '../support/newsletter.po';
+
+describe('Newsletter', () => {
+  it(`Given the user has filled in their email
+    When the "Submit" button is clicked
+    Then the user has sign up for the newsletter`, () => {
+    const email = '[email protected]';
+    cy.visit('/newsletter');
+    newsletter.typeEmail(email);
+
+    newsletter.submit();
+    newsletter
+      .getSubmitMessage()
+      .should('have.text', `Thanks for signing up, ${email}!`);
+  });
+});

apps/analog-app-e2e-cypress/src/support/newsletter.po.ts

@@ -0,0 +1,6 @@
+export const typeEmail = (email: string) =>
+  cy.get('input[name="email"]').type(email);
+
+export const submit = () => cy.contains('button', /submit/i).click();
+
+export const getSubmitMessage = () => cy.get('#signup-message');

apps/analog-app/src/app/pages/newsletter.page.ts

@@ -2,6 +2,8 @@ import { Component, signal } from '@angular/core';
 
 import { FormAction } from '@analogjs/router';
 
+import { type NewsletterSubmitResponse } from './newsletter.server';
+
 type FormErrors =
   | {
       email?: string;
@@ -15,34 +17,37 @@ type FormErrors =
   template: `
     <h3>Newsletter Signup</h3>
 
-    @if (!signedUp()) {
-    <form
-      method="post"
-      (onSuccess)="onSuccess()"
-      (onError)="onError($any($event))"
-      (onStateChange)="errors.set(undefined)"
-    >
-      <div>
-        <label for="email"> Email </label>
-        <input type="email" name="email" />
+    @if (signedUpEmail()) {
+      <div id="signup-message">
+        Thanks for signing up, {{ signedUpEmail() }}!
       </div>
-
-      <button class="button" type="submit">Submit</button>
-    </form>
-
-    @if (errors()?.email) {
-    <p>{{ errors()?.email }}</p>
-    } } @else {
-    <div>Thanks for signing up!</div>
+    } @else {
+      <form
+        method="post"
+        (onSuccess)="onSuccess($any($event))"
+        (onError)="onError($any($event))"
+        (onStateChange)="errors.set(undefined)"
+      >
+        <div>
+          <label for="email"> Email </label>
+          <input type="email" name="email" />
+        </div>
+
+        <button class="button" type="submit">Submit</button>
+      </form>
+
+      @if (errors()?.email) {
+        <p>{{ errors()?.email }}</p>
+      }
     }
   `,
 })
 export default class NewsletterComponent {
-  signedUp = signal(false);
+  signedUpEmail = signal('');
   errors = signal<FormErrors>(undefined);
 
-  onSuccess() {
-    this.signedUp.set(true);
+  onSuccess(res: NewsletterSubmitResponse) {
+    this.signedUpEmail.set(res.email);
   }
 
   onError(result?: FormErrors) {

apps/analog-app/src/app/pages/newsletter.server.ts

@@ -6,6 +6,11 @@ import {
 } from '@analogjs/router/server/actions';
 import { readFormData } from 'h3';
 
+export type NewsletterSubmitResponse = {
+  type: 'success';
+  email: string;
+};
+
 export function load() {
   return {
     loaded: true,
@@ -24,7 +29,5 @@ export async function action({ event }: PageServerAction) {
     return redirect('/');
   }
 
-  console.log({ email: body.get('email') });
-
-  return json({ type: 'success' });
+  return json<NewsletterSubmitResponse>({ type: 'success', email });
 }

packages/router/src/lib/form-action.directive.ts

@@ -61,7 +61,7 @@ export class FormAction {
             const redirectUrl = new URL(res.url).pathname;
             this.state.emit('redirect');
             this.router.navigate([redirectUrl]);
-          } else if (res.headers.get('Content-type') === 'application/json') {
+          } else if (this._isJSON(res.headers.get('Content-type'))) {
             res.json().then((result) => {
               this.onSuccess.emit(result);
               this.state.emit('success');
@@ -95,4 +95,11 @@ export class FormAction {
 
     return `/api/_analog/pages${window.location.pathname}`;
   }
+
+  private _isJSON(contentType: string | null): boolean {
+    const mime = contentType ? contentType.split(';') : [];
+    const essence = mime[0];
+
+    return essence === 'application/json';
+  }
 }