Working with React Components + Props
Tags: 2articles1week, react, components, props
Published: 2023-04-23 11:24:06

---
title: Working with React Components + Props
published: true
date: 2021-03-24 13:05:53 UTC
tags: 2Articles1Week,React,components,props
canonical_url: https://chrisdevcode.hashnode.dev/working-with-react-components-props
---

## What are props?

In simple terms, they are data passed into components.

## When to use props?

When building a react application, the UI is divided into smaller parts called Components.

Some of these components are re-used in various pages or parts of the application, of course with different data/messages/content. For this to be effective, props are used.

For example, a simple react website with two pages, all share a common `<Head>` element:

Home page

![home-page.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1616589188385/rsv7s6Apu.png)

About page ![about-page.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1616589198668/Ezttt6uY_.png)

The two pages share a common `<Header />` component:

```
const Header = ({ head, description }) => {
  return (
    <>
      <div className='starter-template text-center mt-5'>
        <h1>{head} Page</h1>
        <p className='lead text-capitalize'>{description}</p>
      </div>
    </>
  )
}

```

(Don't worry, I'll explain the code 😄 [here](#destructuring))

## Creating a Prop

Consider a sample component below:

```
const Header = () => {
  return (
    <>
      <div className='starter-template text-center mt-5'>
        <h1>Home Page</h1>
        <p className='lead text-capitalize'>Welcome To My Home Page</p>
      </div>
    </>
  )
}

```

The component can be re-used by simply importing it to the page/file and using `<Header />`. The expected results will be:

![header0.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1616589379857/0VcYE3IWQ.png)

Imagine having an application with more than one page, you'd have to write a header component for every page. That shouldn't be the case. Use Props! 😄😄

To be able to re-use the `<h1>Home Page</h1>` and `<p className='lead text-capitalize'>Welcome To My Home Page</p>` with different content in each page, we'll simply pass in props:

```
const Header = (props) => {
  return (
    <>
      <div className='starter-template text-center mt-5'>
        <h1>{props.title} Page</h1>
        <p className='lead text-capitalize'>{props.description}</p>
      </div>
    </>
  )
}

```

We declared `props` as an argument in the function components, and replaced the contents in the `<h1>` and `<p>` elements to use the props. The values replaced, i.e `{props.title}` and `{props.description}` will be used to pass in data dynamically wherever the `Header` component will be used.

On the page where you'll be using the component, you'll simply add attributes to the component: For example on the home page:

```
<Header title='Home' description='This is the Home page' />

```

### destructuring

The New es6 features allows destructuring of props in the components:

```
const Header = ({ title, description }) => {
  return (
    <>
      <div className='starter-template text-center mt-5'>
        <h1>{title} Page</h1>
        <p className='lead text-capitalize'>{description}</p>
      </div>
    </>
  )
}

```

## Defualt Prop values:

[Documentation - Declaring default props](https://reactjs.org/docs/react-without-es6.html#declaring-default-props)

For some reason you may forget to pass in a prop value or something fishy happens in your application. You may want to set up a default prop value to cover up for that.

To do that you simply add:

```
Header.defaultProps = {
  title: 'Page Title',
  description: 'A defualt description',
}

```

This will ensure that your components always have data passed in incase something fishy happens.

## Props Typechecking

> As your app grows, you can catch a lot of bugs with type-checking.

[Documentations - Typechecking with prototypes](https://reactjs.org/docs/typechecking-with-proptypes.html)

To perform this, you have to import prop-type into your components.

```
import PropTypes from 'prop-types';


Header.propTypes = {
  title: PropTypes.string
};

```

You can set a default data-type for a prop with the available options:

```
// You can declare that a prop is a specific JS type. By default, these
  // are all optional.
  optionalArray: PropTypes.array,
  optionalBool: PropTypes.bool,
  optionalFunc: PropTypes.func,
  optionalNumber: PropTypes.number,
  optionalObject: PropTypes.object,
  optionalString: PropTypes.string,
  optionalSymbol: PropTypes.symbol,

  // Anything that can be rendered: numbers, strings, elements or an array
  // (or fragment) containing these types.
  optionalNode: PropTypes.node,

  // A React element.
  optionalElement: PropTypes.element,

  // A React element type (ie. MyComponent).
  optionalElementType: PropTypes.elementType,

  // You can also declare that a prop is an instance of a class. This uses
  // JS's instanceof operator.
  optionalMessage: PropTypes.instanceOf(Message),

  // You can ensure that your prop is limited to specific values by treating
  // it as an enum.
  optionalEnum: PropTypes.oneOf(['News', 'Photos']),

  // An object that could be one of many types
  optionalUnion: PropTypes.oneOfType([
    PropTypes.string,
    PropTypes.number,
    PropTypes.instanceOf(Message)
  ]),

  // An array of a certain type
  optionalArrayOf: PropTypes.arrayOf(PropTypes.number),

  // An object with property values of a certain type
  optionalObjectOf: PropTypes.objectOf(PropTypes.number),

  // An object taking on a particular shape
  optionalObjectWithShape: PropTypes.shape({
    color: PropTypes.string,
    fontSize: PropTypes.number
  }),

  // An object with warnings on extra properties
  optionalObjectWithStrictShape: PropTypes.exact({
    name: PropTypes.string,
    quantity: PropTypes.number
  }),   

  // You can chain any of the above with `isRequired` to make sure a warning
  // is shown if the prop isn't provided.
  requiredFunc: PropTypes.func.isRequired,

  // A required value of any data type
  requiredAny: PropTypes.any.isRequired,

```

### That's all

https://reactjs.org/docs/components-and-props.html

https://reactjs.org/docs/typechecking-with-proptypes.html

Written with 💜 by Chris Achinga

#2Articles1Week