Could anyone show an example of defining defaultProps on a React component class in TypeScript?
interface IProps {}
interface IState {}
class SomeComponent extends Component<IProps, IState> {
// ... defaultProps ?
// public defaultProps: IProps = {}; // This statement produces an error
constructor(props: IProps) {
super(props);
}
// ...
}
You can define default props this way:
export class Counter extends React.Component {
constructor(props) {
super(props);
this.state = {count: props.initialCount};
this.tick = this.tick.bind(this);
}
tick() {
this.setState({count: this.state.count + 1});
}
render() {
return (
<div onClick={this.tick}>
Clicks: {this.state.count}
</div>
);
}
}
Counter.propTypes = { initialCount: React.PropTypes.number };
Counter.defaultProps = { initialCount: 0 };
This is equivalent in TypeScript to defining defaultProps as a static field inside the class body:
class SomeComponent extends Component<IProps, IStates> {
public static defaultProps: IProps = { /* ... */ };
// ...
}
defaultProps. Instead see facebook.github.io/react/docs/react-component.html#defaultprops
jsx, it throws an exception. It works if I make it optional ` title? : String;`... Is that what is suppose to happen?Let say if you have a Movie stateless component then you can define proptype like this below:
const Movie = props => {
return (
<div>
<h3>{props.movie.title}</h3>
</div>
);
};
Movie.propTypes = {
movie: PropTypes.shape({
title: PropTypes.string.isRequired
})
};
Movie. defaultProps = {
movie: PropTypes.shape({})
};
And for class component you can do something like this or you can use the same pattern like above:
export default class Movie extends React.Component {
static propTypes = {
movie: PropTypes.shape({
title: PropTypes.string.isRequired
}),
desc: PropTypes.string
};
static defaultProps = {
desc: 'No movie is available'
};
render() {
return (
<div>
<h3>{this.props.movie.title}</h3>
<h3>{this.props.movie.desc}</h3>
</div>
);
}
}
Movie.defaultProps = { (with an "s")?
I used if-statements to check if the value of the prop was undefined, if so, I set a default value, otherwise I used the value that was passed through.
interface Props {
style: any;
bounces?: boolean | undefined;
extraHeight?: number | undefined;
}
const DynamicView: React.FC<Props> = (props) => {
return (
<KeyboardAwareScrollView
style={props.style}
bounces={
(props.bounces = props.bounces === undefined ? false : props.bounces)
}
extraHeight={
(props.extraHeight =
props.extraHeight === undefined ? 15 : props.extraHeight)
}>
{props.children}
</KeyboardAwareScrollView>
);
};
export default DynamicView;
