React - how to pass props to react components

In this article, we would like to show different ways how to pass props into React components.

Note: in the below example we use function components to show main idea.

Values can be passed as props using:

1. single or double apostrophes syntax ('' or "") - that let us use only string values,
2. curly brackets syntax ({}) that let us pass:
   • values with different types,
   • variables,
3. spread syntax (...) that syntax that reduces the time needed to create a new component - read more about spread syntax here.

Quick solution: 

const admin = { name: 'Tom', age: 30 };

<User name='Kate' age='25' />              // single apostrophes syntax
<User name="Kate" age="25" />              // double apostrophes syntax

<User name="John" age={25} />              // literals with curly brackets syntax
<User name="Chris" age={'25'} />           // literals with curly brackets syntax
<User name={admin.name} age={admin.age} /> // variable with curly brackets syntax

<User {...admin} />                        // spread syntax

Read below sections to see how different cases work in details.

Practical examples

1. Single or double apostrophes example

JSX lets us use '' or "" when we pass props values. The main idea of this approach is to simplify string-valued props usage.

So component creation should look like:

<User name="Kate" age="25" />

Practical example:

// ONLINE-RUNNER:browser;

// Note: Uncomment import lines during working with JSX Compiler.
// import React from 'react';
// import ReactDOM from 'react-dom';
   
const User = ({ name, age }) => {
	return (
		<div>
			<span>{name} ({typeof name})</span>,{' '}
			<span>{age} ({typeof age})</span>
		</div>
	)
};

const App = () => {
	return (
		<div>
			<User name="Kate" age="25" />
		</div>
	);
};

const root = document.querySelector('#root');
ReactDOM.render(<App />, root );

2. Curly brackets example

That approach lets us pass values with different types as props. Each prop can get value from literal or some variable.

So component creation should look like:

// const admin = { name: 'Tom', age: 30 };

<User name="John" age={25} />
<User name="Chris" age={'25'} />
<User name={admin.name} age={admin.age} />

Where age={'25'} is equal to age="25" syntax.

Practical example:

// ONLINE-RUNNER:browser;

// Note: Uncomment import lines during working with JSX Compiler.
// import React from 'react';
// import ReactDOM from 'react-dom';
   
const User = ({ name, age }) => {
	return (
		<div>
			<span>{name} ({typeof name})</span>,{' '}
			<span>{age} ({typeof age})</span>
		</div>
	)
};

const App = () => {
	const admin = { name: 'Tom', age: 30 };
	return (
		<div className="App">
			<User name="John" age={25} />
			<User name="Chris" age={'25'} />
			<User name={admin.name} age={admin.age} />
		</div>
  );
};

const root = document.querySelector('#root');
ReactDOM.render(<App />, root );

3. Spread syntax example

That case let us avoid typing many object props one after one and pass them using one operation.

So component creation should look like:

// const admin = { name: 'Tom', age: 30 };

<User {...admin} />

Practical example:

// ONLINE-RUNNER:browser;

// Note: Uncomment import lines during working with JSX Compiler.
// import React from 'react';
// import ReactDOM from 'react-dom';
   
const User = ({ name, age }) => {
	return (
		<div>
			<span>{name} ({typeof name})</span>,{' '}
			<span>{age} ({typeof age})</span>
		</div>
	)
};

const App = () => {
  const admin = { name: 'Tom', age: 30 };
  return (
	<div>
	  <User {...admin} />
	</div>
  );
};

const root = document.querySelector('#root');
ReactDOM.render(<App />, root );