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Abdul Haseeb
Abdul Haseeb

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How to reuse component's props in TypeScript

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We often find ourself defining types for the props that are not actually part of that component and are used in some other component.

Lets take a simple example:
Suppose we have a Parent and a Child component with following props.

import React from 'react';
import { Child } from './Child';

type Props = {
  greeting: string;
  firstName: string;
  lastName: string;
};

export const Parent: React.FC<Props> = ({ greeting, firstName, lastName }) => {
  return (
    <>
      <span> {greeting}</span>
      <Child firstName={firstName} lastName={lastName} />
    </>
  );
};
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import React from 'react';

type Props = {
  firstName: string;
  lastName: string;
};

export const Child: React.FC<Props> = ({ firstName, lastName }) => {
  return (
    <>
      <div>{firstName}</div>
      <div>{lastName}</div>
    </>
  );
};

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⚠️ Problem Statement:

Repetitive Props

  • Type for firstName and lastName are also defined in Parent because it needs to be passed down to the Child component.

Code Sync issues

  • If one part changes we need to make sure the others stays in sync.

  • If the Child component is used in a similar pattern elsewhere we need to make sure we update the props there too.

💡 Solution:

We can use ComponentProps to extract the Props directly form the component's type and use rest and spread syntax to avoid repetition.

import React, { ComponentProps } from 'react';
import { Child } from './Child';

type Props = ComponentProps<typeof Child> & {
  greeting: string;
};

export const Parent: React.FC<Props> = ({ greeting, ...childProps }) => {
  return (
    <>
      <span> {greeting}</span>
      <Child {...childProps} />
    </>
  );
};
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Benefits:

  • Creating the parent's props by merging them with it's child's solves the code sync issues.
  • Makes a unique source of truth.

PS: If you only need some of the props in the Child component, you can use Partials.

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