How to properly use fontawesome on React js?

As written in font awesome documentation, you can easily use it like this:

First, install the package by:

npm install @fortawesome/fontawesome-svg-core
npm install @fortawesome/free-solid-svg-icons
npm install @fortawesome/react-fontawesome

Then you can use it like this:

  // Light:
  <FontAwesomeIcon icon={["fal", "coffee"]} />
  // Regular:
  <FontAwesomeIcon icon={["far", "coffee"]} />
  // Solid
  <FontAwesomeIcon icon={["fas", "coffee"]} />
  // ...or, omit as FontAwesome defaults to solid, so no need to prefix:
  <FontAwesomeIcon icon="coffee" />
  // Brand:
  <FontAwesomeIcon icon={["fab", "github"]} />

You can also use it like this:

import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'
import { faCoffee } from '@fortawesome/free-solid-svg-icons'

const element = <FontAwesomeIcon icon={faCoffee} />

Sizing:

  <FontAwesomeIcon icon="coffee" size="xs" />
  <FontAwesomeIcon icon="coffee" size="lg" />
  <FontAwesomeIcon icon="coffee" size="6x" />

You can use it like this;

import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'
import { faCoffee } from '@fortawesome/free-solid-svg-icons'

<FontAwesomeIcon icon={faCoffee} />

You have to import icon. You can see detailed usage on docs.