FormDataEvent - Web APIs

FormDataEvent - Web APIs | MDN

Constructor

FormDataEvent(): Creates a new FormDataEvent object instance.

Instance properties

Inherits properties from its parent interface, Event.

FormDataEvent.formData: Contains the FormData object representing the data contained in the form when the event was fired.

Instance methods

Inherits methods from its parent interface, Event.

Examples

// grab reference to form

const formElem = document.querySelector("form");

// submit handler

formElem.addEventListener("submit", (e) => {
  // on form submission, prevent default
  e.preventDefault();

  console.log(form.querySelector('input[name="field1"]')); // FOO
  console.log(form.querySelector('input[name="field2"]')); // BAR

  // construct a FormData object, which fires the formdata event
  const formData = new FormData(formElem);
  // formdata gets modified by the formdata event
  console.log(formData.get("field1")); // foo
  console.log(formData.get("field2")); // bar
});

// formdata handler to retrieve data

formElem.addEventListener("formdata", (e) => {
  console.log("formdata fired");

  // modifies the form data
  const formData = e.formData;
  formData.set("field1", formData.get("field1").toLowerCase());
  formData.set("field2", formData.get("field2").toLowerCase());
});