te')); return $arr; } /* 遍历用户所有主题 * @param $uid 用户ID * @param int $page 页数 * @param int $pagesize 每页记录条数 * @param bool $desc 排序方式 TRUE降序 FALSE升序 * @param string $key 返回的数组用那一列的值作为 key * @param array $col 查询哪些列 */ function thread_tid_find_by_uid($uid, $page = 1, $pagesize = 1000, $desc = TRUE, $key = 'tid', $col = array()) { if (empty($uid)) return array(); $orderby = TRUE == $desc ? -1 : 1; $arr = thread_tid__find($cond = array('uid' => $uid), array('tid' => $orderby), $page, $pagesize, $key, $col); return $arr; } // 遍历栏目下tid 支持数组 $fid = array(1,2,3) function thread_tid_find_by_fid($fid, $page = 1, $pagesize = 1000, $desc = TRUE) { if (empty($fid)) return array(); $orderby = TRUE == $desc ? -1 : 1; $arr = thread_tid__find($cond = array('fid' => $fid), array('tid' => $orderby), $page, $pagesize, 'tid', array('tid', 'verify_date')); return $arr; } function thread_tid_delete($tid) { if (empty($tid)) return FALSE; $r = thread_tid__delete(array('tid' => $tid)); return $r; } function thread_tid_count() { $n = thread_tid__count(); return $n; } // 统计用户主题数 大数量下严谨使用非主键统计 function thread_uid_count($uid) { $n = thread_tid__count(array('uid' => $uid)); return $n; } // 统计栏目主题数 大数量下严谨使用非主键统计 function thread_fid_count($fid) { $n = thread_tid__count(array('fid' => $fid)); return $n; } ?>reactjs - createPortal - TypeScript document.getElementById type issue when JavaScript runs fine? - Stack Overflow

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    I'm trying to use ReactDOM.createPortal and neither 'ReactDOM' or 'document' is highlighted in VSCode and I get this error when hovering over 'document.getElementById('overlay-root')':

    Argument of type 'HTMLElement | null' is not assignable to parameter of type 'Element'.
  Type 'null' is not assignable to type 'Element'.

    Here's the code:

    import styles from './CartModal.module.css';
import ReactDOM from 'react-dom';
import Card from '../UI/Card/Card';

interface CartModalProps {
  onClose?: () => void
}

const DisplayCartModal: React.FC<CartModalProps> = (props) => {

  return ReactDOM.createPortal(
    <>
      <CartModal />
    </>, 
    document.getElementById('overlay-root')
  )
}

export default DisplayCartModal;

    I've tried switching the file extension to .js to see if this is a TypeScript error and indeed when I changed it (and removed TS-specific syntax) everything was highlighted and worked perfectly. It did not return null, it returned the correct HTML Element. Help is greatly appreciated!

    I'm trying to use ReactDOM.createPortal and neither 'ReactDOM' or 'document' is highlighted in VSCode and I get this error when hovering over 'document.getElementById('overlay-root')':

    Argument of type 'HTMLElement | null' is not assignable to parameter of type 'Element'.
  Type 'null' is not assignable to type 'Element'.

    Here's the code:

    import styles from './CartModal.module.css';
import ReactDOM from 'react-dom';
import Card from '../UI/Card/Card';

interface CartModalProps {
  onClose?: () => void
}

const DisplayCartModal: React.FC<CartModalProps> = (props) => {

  return ReactDOM.createPortal(
    <>
      <CartModal />
    </>, 
    document.getElementById('overlay-root')
  )
}

export default DisplayCartModal;

    I've tried switching the file extension to .js to see if this is a TypeScript error and indeed when I changed it (and removed TS-specific syntax) everything was highlighted and worked perfectly. It did not return null, it returned the correct HTML Element. Help is greatly appreciated!

    • javascript
    • reactjs
    • typescript
    Share Improve this question edited Sep 1, 2021 at 3:48 Ryan Le 8,4121 gold badge17 silver badges27 bronze badges asked Sep 1, 2021 at 3:28 Connor MooneyhanConnor Mooneyhan 5576 silver badges17 bronze badges
    Add a ment  | 

    2 Answers 2

    Reset to default 10

    The issue is, document.getElementById('overlay-root') might be null. You (I assume) know that it will not be, but Typescript does not know that.

    You can assert that not-null-ness with an exclamation mark, like so:

    ReactDOM.createPortal(
<>
  <CartModal />
</>, 
document.getElementById('overlay-root')!
)

    If your assertion is false, you will get a run-time error, a very bad thing.

    In typescript, createPortal receive container of type Element:

    export function createPortal(children: ReactNode, container: Element, key?: null | string): ReactPortal;

    Meanwhile, document.querySelector return an Element OR Null

    querySelector<E extends Element = Element>(selectors: string): E | null;

    This is a mismatch for both, to fix this, you will need to cast the return object from querySelector

    document.querySelector('#overlay-root') as Element,

    But for the sake of catching any errors, you should check for null before using it so you won't have to cast at all:

    const DisplayCartModal: React.FC<CartModalProps> = (props) => {
  const overlayRootEl = document.querySelector('#overlay-root');

  return overlayRootEl
    ? ReactDOM.createPortal(
      <>
        <CartModal />
      </>,
      overlayRootEl,
    )
    : null;
};

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