How to prevent Modal from closing?

Modal and Drawer components' opened state is controlled by the opened prop. You can use it to prevent the modal from closing by setting it to true. For example, this can be useful if you have an async operation inside the modal and want to prevent the user from closing it before the operation is finished:

import { useState } from 'react';
import { useDisclosure } from '@mantine/hooks';
import { Button, Modal } from '@mantine/core';

function operation() {
  return new Promise((resolve) => {
    setTimeout(resolve, 5000);
  });
}

function Demo() {
  const [opened, { open, close }] = useDisclosure();
  const [loading, setLoading] = useState(false);

  const performOperation = () => {
    setLoading(true);
    operation().then(() => setLoading(false));
  };

  return (
    <>
      <Modal
        opened={opened}
        onClose={loading ? () => {} : close}
        withCloseButton={!loading}
        title="Modal with async operation"
      >
        <Button loading={loading} onClick={performOperation} fullWidth>
          Perform heavy operation
        </Button>
      </Modal>
      <Button onClick={open}>Open modal</Button>
    </>
  );
}