Learning React? Download my free React Handbook 🔥

Very simple example of a form that accepts a GitHub username and once it receives a submit event, it asks the GitHub API for the user information, and prints them.

This code creates a reusable Card component. When you enter a name in the input field managed by the Form component, this name is bound to its state.

When Add card is pressed, the input form is cleared by clearing the userName state of the Form component.

The example uses, in addition to React, the Axios library. It’s a nice useful and lightweight library to handle network requests. Add it to the Pen settings in Codepen, or install it locally using npm install axios.

Output

The React example output

Code

We start by creating the Card component, the one that will display our image and details as gathered from GitHub. It gets its data via props, using

  • props.avatar_url the user avatar
  • props.name the user name
  • props.blog the user website URL
const Card = props => {
  return (
    <div style={{ margin: '1em' }}>
      <img alt="avatar" style={{ width: '70px' }} src={props.avatar_url} />
      <div>
        <div style={{ fontWeight: 'bold' }}>{props.name}</div>
        <div>{props.blog}</div>
      </div>
    </div>
  )
}

We create a list of those components, which will be passed by a parent component in the cards prop to CardList, which iterates on it using map() and outputs a list of cards:

const CardList = props => (
  <div>
    {props.cards.map(card => (
      <Card {...card} />
    ))}
  </div>
)

The parent component is App, which stores the cards array in its own state, managed using the useState() Hook:

const App = () => {
  const [cards, setCards] = useState([])

  return (
    <div>
      <CardList cards={cards} />
    </div>
  )
}

Cool! We must have a way now to ask GitHub for the details of a single username. We’ll do so using a Form component, where we manage our own state (username), and we ask GitHub for information about a user using their public APIs, via Axios:

const Form = props => {
  const [username, setUsername] = useState('')

  handleSubmit = event => {
    event.preventDefault()

    axios.get(`https://api.github.com/users/${username}`).then(resp => {
      props.onSubmit(resp.data)
      setUsername('')
    })
  }

  return (
    <form onSubmit={handleSubmit}>
      <input
        type="text"
        value={username}
        onChange={event => setUsername(event.target.value)}
        placeholder="GitHub username"
        required
      />
      <button type="submit">Add card</button>
    </form>
  )
}

When the form is submitted we call the handleSubmit event, and after the network call we call props.onSubmit passing the parent (App) the data we got from GitHub.

We add it to App, passing a method to add a new card to the list of cards, addNewCard, as its onSubmit prop:

const App = () => {
  const [cards, setCards] = useState([])

  addNewCard = cardInfo => {
    setCards(cards.concat(cardInfo))
  }

  return (
    <div>
      <Form onSubmit={addNewCard} />
      <CardList cards={cards} />
    </div>
  )
}

Finally we render the app:

ReactDOM.render(<App />, document.getElementById('app'))

Here is the full source code of our little React app:

const { useState } = React

const Card = props => {
  return (
    <div style={{ margin: '1em' }}>
      <img alt="avatar" style={{ width: '70px' }} src={props.avatar_url} />
      <div>
        <div style={{ fontWeight: 'bold' }}>{props.name}</div>
        <div>{props.blog}</div>
      </div>
    </div>
  )
}

const CardList = props => <div>{props.cards.map(card => <Card {...card} />)}</div>

const Form = props => {
  const [username, setUsername] = useState('')

  handleSubmit = event => {
    event.preventDefault()

    axios
      .get(`https://api.github.com/users/${username}`)
      .then(resp => {
        props.onSubmit(resp.data)
        setUsername('')
      })
  }

  return (
    <form onSubmit={handleSubmit}>
      <input
        type="text"
        value={username}
        onChange={event => setUsername(event.target.value)}
        placeholder="GitHub username"
        required
      />
      <button type="submit">Add card</button>
    </form>
  )
}

const App = () => {
  const [cards, setCards] = useState([])

  addNewCard = cardInfo => {
    setCards(cards.concat(cardInfo))
  }

  return (
    <div>
      <Form onSubmit={addNewCard} />
      <CardList cards={cards} />
    </div>
  )
}

ReactDOM.render(<App />, document.getElementById('app'))

Check it out on Codepen at https://codepen.io/flaviocopes/pen/oJLyeY

Found a typo or problem? Edit this page