What is the significance of passing an argument within curly braces in the renderItem function of React Native's Flat List component?

This specific scenario entails:

   const blocks = [
  {id: 0, content: 'HTML'},
  {id: 1, content: 'CSS'},
  {id: 2, content: 'JavaScript'},
  {id: 3, content: 'React'},
  {id: 4, content: 'Angular'},
]

const getKey = ({id}) => id

export default class Website extends Component {

  showBlock = ({item}) => {
    return (
      <Text style={styles.block}>
        {item.content}
      </Text>
    )
  }

  render() {
    return (
      <FlatList
        style={styles.page}
        data={blocks}
        renderItem={this.showBlock}
        keyExtractor={getKey}
      />
    );
  }
}

const styles = StyleSheet.create({
  page: {
    marginTop: 20,
    flex: 1,
  },
  block: {
    padding: 15,
    marginBottom: 5,
    backgroundColor: 'lightgray',
  },
})

found on ,

What's the reason for defining renderItem as a function that takes ({item}) instead of just (item)? Aren't arrow functions supposed to receive arguments in "()"? What is the significance of "{}" here? If removed, it results in the text within each FlatList item disappearing.

Answer №1

One of the interesting features introduced in ES6 is known as Destructuring

Destructuring assignment syntax in JavaScript allows for unpacking values from arrays or properties from objects into separate variables.

Source

Essentially, it provides a convenient shortcut to access keys within an object passed as a parameter to a function.

For example:

const foo = {
  bar: "hello world"
};

function basic(arg) {
  const bar = arg.bar;
  console.log(bar);
};

function destructuring({bar}) {
// no need to define a bar variable here, as 'bar' is directly available!
  console.log(bar);
};

basic(foo);
destructuring(foo);

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