Date: Dec 14, 2022

Hello and welcome to this blog I am writing this blog as a revision for react So today we are going to re-visit a topic in react call props

So the first question is why do we need props ?

• props make our data , component reusable
• props are immutable
• data passed from outside of component

How to pass props at a very basic level

<CustomComponent name="radhe-krishna" />

• so here we are passing prop -> name in custom component
• where name is the key and radhe-krishna is value
• Internally every jsx element transpiles to object(POJO)
• therefore , props are nothing but objects with key value pair

How to access props in a component ?

Consuming props in a Component

function CustomComponent(props) {
	return <div>{props.name}</div>;
}

• prop is an object , so to access the values of props we can use dot operator
• But why props.name ?
• remember we wrote our key as name
• so basically we are using that key to access the value(prop) we defined in custom component
• As we already know component transpile to object ? right! so props is pre-defined key-name inside JSX object
• whenever we pass any props to custom component , we can access the prop using props.propName

do you know before react we having been using props in native html elements like anchor(href),img(src)

can we use custom props in native DOM elements ?

• Repeat After me, NO! we can’t pass custom props to native dom elements

Basic Introduction Completed!

Advance Props Guide

Before learning more about props , we can have one small basic props exercise, so here you go

- open code sandbox (react environment)
- make a custom component call `Info.jsx`
- render the custom component in app
- pass basic details `firstname, lastname, age, city, profession` as a prop
- consume that information in `Info` component and display

I myself is doing this mini-exercise while writing this article 😃🥳

My solution for exercise

If you did it ? Well Done! you know props If got stuck with non-string props or destructuring no worries we will cover this together, continue reading 😊

A Friendly Water Reminder if you haven’t

What did you learn new with that exercise ?

• Passing non-string props, multiple props, consuming multiple props
• Let me dissect it step by step
• From the previous exercise, I passed props to custom component in this way :

<Info
	firstName="Dheeraj"
	lastName="Purohit"
	age="23"
	city="Mumbai"
	profession="Developer"
/>

• Well Everything was in double quotes ""
• Also called as String Props
• We could do it differently for non-string props like age or any boolean props

Non-String and Multiple Props

A) Non-String

<Info
	firstName="Dheeraj"
	lastName="Purohit"
	age={23}
	isIndian={true}
	city="Mumbai"
	profession="Developer"
/>

• Did you noticed we added {} braces around non-string props values
• hey but still it looks weird right ? we are passing multiple props affecting the readability.

B) Multiple Props

export default function App() {
	const propsData = {
		firstName: "Dheeraj",
		lastName: "Purohit",
	};

	return (
		<div className="App">
			<Info {...propsData} />
		</div>
	);
}

• For Multiple props we can store our props value in object
• propsData is an object having our props value
• We are passing multiple props to Info component using object spread operator, so simple and readable right!

javaScript info for spread syntax

PAY ATTENTION!

3) Consuming multiple Props and Object as a Prop

A) Consuming Multiple Props

export function Info(props) {
	const {
		firstName,
		lastName,
		age,
		city,
		profession,
		isIndian,
	} = props;

	return (
		<div>
			<ul>
				<li>{firstName}</li>
				<li>{lastName}</li>
				<li>{age}</li>
				<li>{city}</li>
				<li>{profession}</li>
				<li>{isIndian ? "Indian" : "Non-Indian"}</li>
			</ul>
		</div>
	);
}

• we can consume multiple props using object destructuring
• const { firstName, lastName, age, city, profession, isIndian } = props
• after destructuring we can directly use the name of props in UI part of (after return element)

B) Using Multiple Props (Object) without destructuring

• there are multiple patterns followed in react , so destructuring is one of them
• we can also access prop value by using props.keyName.propsName
• Lets see how to do that

export default function App() {
	const propsData = {
		firstName: "Dheeraj",
		lastName: "Purohit",
	};

	return (
		<div className="App">
			<Info propsData={propsData} />
		</div>
	);
}

• we are passing props our old key value pair
• propsData is key for props
• now lets consume it

export function Info(props) {
	return (
		<div>
			<ul>
				<li>{props.propsData.firstName}</li>
				<li>{props.propsData.lastName}</li>
			</ul>
		</div>
	);
}

• remember i mentioned we are going to use props.keyName.propsName
• so here we are directly using props
• re-iterating props is general key for accessing props propsData is our keyName and propsName are firstName and lastName

Refactoring time

• we have learned something new , so to make it concrete try to refactor the previous exercise and see how readable our code becomes.

Ending Note!
- i might have missed some parts of props, but tried to put it here as a part of my revision
- if you find this article helpful, like, share with others who is learning react
- if you find any spelling mistake, wrong term used do let me know in comments and your feedback about this blog

Happy Coding
Jai Shri Krishna🙏💜