`useSubmit`

The imperative version of <Form> that lets you, the programmer, submit a form instead of the user.

This feature only works if using a data router, see Picking a Router

For example, submitting the form every time a value changes inside the form:

import { useSubmit, Form } from "react-router-dom";

function SearchField() {
  let submit = useSubmit();
  return (
    <Form
      onChange={(event) => {
        submit(event.currentTarget);
      }}
    >
      <input type="text" name="search" />
      <button type="submit">Search</button>
    </Form>
  );
}

This can also be useful if you'd like to automatically sign someone out of your website after a period of inactivity. In this case, we've defined inactivity as the user hasn't navigated to any other pages after 5 minutes.

import { useSubmit, useLocation } from "react-router-dom";
import { useEffect } from "react";

function AdminPage() {
  useSessionTimeout();
  return <div>{/* ... */}</div>;
}

function useSessionTimeout() {
  const submit = useSubmit();
  const location = useLocation();

  useEffect(() => {
    const timer = setTimeout(() => {
      submit(null, { method: "post", action: "/logout" });
    }, 5 * 60_000);

    return () => clearTimeout(timer);
  }, [submit, location]);
}

Submit target

The first argument to submit accepts many different values.

You can submit any form or form input element:

// input element events
<input onChange={(event) => submit(event.currentTarget)} />;

// React refs
let ref = useRef();
<button ref={ref} />;
submit(ref.current);

You can submit FormData:

let formData = new FormData();
formData.append("cheese", "gouda");
submit(formData);

Or you can submit URLSearchParams:

let searchParams = new URLSearchParams();
searchParams.append("cheese", "gouda");
submit(searchParams);

Or anything that the URLSearchParams constructor accepts:

submit("cheese=gouda&toasted=yes");
submit([
  ["cheese", "gouda"],
  ["toasted", "yes"],
]);

The default behavior if you submit a JSON object for a POST submission is to encode the data into FormData:

submit(
  { key: "value" },
  {
    method: "post",
    encType: "application/x-www-form-urlencoded",
  }
);
// will serialize into request.formData() in your action
// and will show up on useNavigation().formData during the navigation

Or you can opt-into JSON encoding:

submit(
  { key: "value" },
  { method: "post", encType: "application/json" }
);
// will serialize into request.json() in your action
// and will show up on useNavigation().json during the navigation

submit('{"key":"value"}', {
  method: "post",
  encType: "application/json",
});
// will encode into request.json() in your action
// and will show up on useNavigation().json during the navigation

Or plain text:

submit("value", { method: "post", encType: "text/plain" });
// will serialize into request.text() in your action
// and will show up on useNavigation().text during the navigation

Submit options

The second argument is a set of options that map (mostly) directly to form submission attributes:

submit(null, {
  method: "post",
  action: "/logout",
});

// same as
<Form action="/logout" method="post" />;

Please see the Splat Paths section on the useResolvedPath docs for a note on the behavior of the future.v7_relativeSplatPath future flag for relative useSubmit() action behavior within splat routes

Because submissions are navigations, the options may also contain the other navigation related props from <Form> such as:

fetcherKey
navigate
preventScrollReset
relative
replace
state
viewTransition

`options.flushSync`

The flushSync option tells React Router DOM to wrap the initial state update for this submission in a ReactDOM.flushSync call instead of the default React.startTransition. This allows you to perform synchronous DOM actions immediately after the update is flushed to the DOM.