Passing Submission Data

Formbase stores every submission, but sometimes you want the values immediately after submit to personalize the next screen. You can do this in two ways:

Use the existing form data in the browser
Submit from the server and use the JSON response

Client-side data (fastest)

Use the values you already have in the browser and redirect with state or query params.

const formData = new FormData(formElement);

const response = await fetch('https://formbase.dev/s/YOUR_FORM_ID', {
  method: 'POST',
  body: formData,
  redirect: 'manual',
});

if (response.status === 303 || response.ok) {
  sessionStorage.setItem('lastSubmission', JSON.stringify({
    email: formData.get('email'),
  }));
  window.location.href = '/thanks';
}

On your thank-you page, read sessionStorage and render a personalized message.

Server-side data (structured)

Submit from your server and return the JSON payload to your client.

const response = await fetch('https://formbase.dev/s/YOUR_FORM_ID', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ email: '[email protected]' }),
});

const result = await response.json();
// result.data contains the submitted object

This is the best option when you need a reliable JSON response.

Browser requests receive a redirect instead of JSON. Use a server action or API route if you need the response body.

Dynamic URL Parameters Conditional Redirects

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Passing Submission Data