Mastering Children Props in TypeScript

Understanding Children in JSX

In JSX, children refer to the content passed between the opening and closing tags of an element. For example:

<Border>
  Hey, I represent the JSX children!
</Border>

In this example, the string “Hey, I represent the JSX children!” is the child of the Border component.

Supported Children Types

JSX supports several types of children, including:

• Strings
• JSX elements
• JavaScript expressions
• Functions

Typing Children Props

When it comes to typing children props, there are several options available. However, manually typing the children prop can be tedious and may not fully represent the children prop. For example:

interface Props {
  children: string | JSX.Element | JSX.Element[] | ((props: any) => JSX.Element);
}

A better approach is to use the PropsWithChildren type provided by React. This type takes your component props and returns a union type with the children prop appropriately typed.

Using the PropsWithChildren Type

The PropsWithChildren type is the recommended way to type children props. It’s less boilerplate and implicitly types the children prop. Here’s an example:

import { PropsWithChildren } from 'eact';

interface FooProps {
  foo: string;
}

interface FooPropsWithChildren extends PropsWithChildren {}

const Foo = ({ children, foo }: FooPropsWithChildren) => {
  return (
    <div>
      {children}
      <p>Foo: {foo}</p>
    </div>
  );
};

Alternative Approaches

While PropsWithChildren is the recommended way to type children props, there are alternative approaches available. These include:

• Using the ReactNode type
• Using the FunctionComponent (or FC) type
• Using the Component type for class components
• Using ReactElement
• Using JSX.Element

Each of these approaches has its own trade-offs, and the choice ultimately depends on your specific use case.

Wrapper Components with TypeScript

Wrapper components are simple higher-order components used to wrap other components for easy interaction. When dealing with TypeScript, wrapper components can improve type safety, especially when handling complex children structures.

Passing Components as Props in TypeScript

Passing components as props in React often means using the React.FC type, which helps create reusable, strongly typed components that can accept other components as their props.

Cloning and Updating Children Components

TypeScript offers minimal help managing issues with React.cloneElement. However, it can still be used to clone and update child components.