isValidElement

const isElement = isValidElement(value)

• Viite
  • isValidElement(value)
• Käyttö
  • Checking if something is a React element

Viite

isValidElement(value)

Call isValidElement(value) to check whether value is a React element.

import { isValidElement, createElement } from 'react';

// ✅ React elements
console.log(isValidElement(<p />)); // true
console.log(isValidElement(createElement('p'))); // true

// ❌ Not React elements
console.log(isValidElement(25)); // false
console.log(isValidElement('Hello')); // false
console.log(isValidElement({ age: 42 })); // false

See more examples below.

Parametrit

• value: The value you want to check. It can be any a value of any type.

Palautukset

isValidElement returns true if the value is a React element. Otherwise, it returns false.

Rajoitukset

• Only JSX tags and objects returned by createElement are considered to be React elements. For example, even though a number like 42 is a valid React node (and can be returned from a component), it is not a valid React element. Arrays and portals created with createPortal are also not considered to be React elements.

Käyttö

Checking if something is a React element

Call isValidElement to check if some value is a React element.

React elements are:

• Values produced by writing a JSX tag
• Values produced by calling createElement

For React elements, isValidElement returns true:

import { isValidElement, createElement } from 'react';

// ✅ JSX tags are React elements
console.log(isValidElement(<p />)); // true
console.log(isValidElement(<MyComponent />)); // true

// ✅ Values returned by createElement are React elements
console.log(isValidElement(createElement('p'))); // true
console.log(isValidElement(createElement(MyComponent))); // true

Any other values, such as strings, numbers, or arbitrary objects and arrays, are not React elements.

For them, isValidElement returns false:

// ❌ These are *not* React elements
console.log(isValidElement(null)); // false
console.log(isValidElement(25)); // false
console.log(isValidElement('Hello')); // false
console.log(isValidElement({ age: 42 })); // false
console.log(isValidElement([<div />, <div />])); // false
console.log(isValidElement(MyComponent)); // false

It is very uncommon to need isValidElement. It’s mostly useful if you’re calling another API that only accepts elements (like cloneElement does) and you want to avoid an error when your argument is not a React element.

Unless you have some very specific reason to add an isValidElement check, you probably don’t need it.

function MyComponent() {
  // ... you can return any React node ...
}

function MyComponent() {
  return 42; // It's ok to return a number from component
}