HTML JSON form submission polyfill based on W3C HTML JSON form submission unofficial draft.

This is an early stage project.

There are two ways of using JSONFormData object, both similar to usual form submission process.

Once polyfill is included on a page, it's possible to submit a form asynchronously with minimum amount of JavaScript code.

<form enctype='application/json' action="/person" method="post">
    <input type="text" name="firstName">
    <input type="text" name="lastName">
    <button type="submit">Submit</button>
</form>

var form = document.querySelector('form');

new JSONFormData(form, (error, response) => {
    // Callback is called when response or error is received
});

• enctype application/json ― set request Content-Type header for JSON data.
• action url ― request endpoint.
• method GET POST PUT DELETE ― HTTP request method.

Both PUT and DELETE HTTP methods were removed in HTML5, but it makes sense to provide them for JSON form submission, which nicely fits CRUD approach.

Form data can be sent manually, similar to a way of sending FormData object. The data is stored in JSONFormData.formData.

form.addEventListener('submit', function (e) {

    const formData = new JSONFormData(form).formData;
    
    fetch("/api", {
      method: "POST",
      body: JSON.stringify(formData),
      headers: {
        "Content-Type": "application/json"
      }
    });
}, false);