form.md

Having components participate in form

Though form elements in @carbon/web-components (e.g. <cds-text-input>) are not native form elements like <input>, they have some extra APIs that align well with web/framework standards.

formdata event

Browsers supporting formdata event fire that event when the user clicks on <button type="submit"> in <form>. Our form components listen to that event to add their values to the <form>.

To support other browsers, you can use a regular <button> and manually fire a custom event with the same name (formdata), like below:

const form = document.querySelector('form');
const button = form.querySelector('button');
button.addEventListener('click', () => {
  const formData = new FormData(form);
  const event = new CustomEvent('formdata', {
    bubbles: true,
    cancelable: false,
    composed: false,
  });
  event.formData = formData;
  form.dispatchEvent(event);
  // `formData` is populated with the data in components such as `<cds-text-input>` or `<cds-dropdown>`, etc. in the `<form>`.
  // You can use `formData` with `fetch()`/XHR instead of letting `<form>` submit the data
});