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ReactJS Props Validation

The ReactJS use PropTypes to validate and specify the expected types of props that a component should receive. PropTypes help catch potential runtime errors and make your code more robust. PropTypes are available through the prop-types library, which you can install separately if it’s not already included in your project.

Here’s how to use PropTypes for props validation in React:

  1. Install the prop-types Library: First, you need to install the prop-types library if it’s not already installed in your project. You can do this using npm or yarn:
Bash
 npm install prop-types

or

Bash
 yarn add prop-types
  1. Import PropTypes: In your component file, import PropTypes from the prop-types library:
TypeScript
 import PropTypes from 'prop-types';
  1. Define PropTypes for Your Component: Below your component code, you can define PropTypes using the PropTypes object. You specify the expected data types for each prop, and you can also indicate whether a prop is required. Here’s an example of defining PropTypes for a component:
TypeScript
 import React from 'react';
 import PropTypes from 'prop-types';

 function MyComponent(props) {
   return <div>Hello, {props.name}!</div>;
 }

 MyComponent.propTypes = {
   name: PropTypes.string.isRequired, // String prop that is required
 };

 export default MyComponent;

In this example, the name prop is expected to be a string, and it’s marked as required using isRequired. If the name prop is missing or not a string, a warning will be shown in the console during development.

  1. Using Various PropTypes: PropTypes provides a variety of type checkers you can use:
  • PropTypes.string: Expects a string.
  • PropTypes.number: Expects a number.
  • PropTypes.bool: Expects a boolean.
  • PropTypes.array: Expects an array.
  • PropTypes.object: Expects an object.
  • PropTypes.func: Expects a function.
  • PropTypes.symbol: Expects a symbol.
  • PropTypes.element: Expects a React element.
  • PropTypes.instanceOf(SomeClass): Expects an instance of a specific class.
  • PropTypes.oneOf(['value1', 'value2']): Expects one of the provided values.
  • PropTypes.oneOfType([PropTypes.string, PropTypes.number]): Expects one of the specified types.
  • PropTypes.arrayOf(PropTypes.number): Expects an array of a specific type.
  • PropTypes.objectOf(PropTypes.string): Expects an object with specific types for its values.
  • PropTypes.shape({ key: PropTypes.string, age: PropTypes.number }): Expects an object with specific keys and types.
  1. Default Props: You can also specify default values for props using the defaultProps property of your component:
TypeScript
 MyComponent.defaultProps = {
   name: 'Guest',
 };

If the parent component does not provide the name prop, it will default to ‘Guest’.

By defining PropTypes for your components, you make your code more self-documenting and help catch potential issues early in the development process, improving the reliability and maintainability of your React applications.

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