What happens in this example?

Question

React

class Timer extends React.Component {

    state = {
        value: 0
    }

    subscription = undefined;

    componentWillMount() {
        this.subscription = Rx.Observable.timer(0, 1000).timestamp().subscribe(::this.setState);
    }

    componentWillUnmount() {
        this.subscription.dispose();
    }

    render() {
        return <div>{ this.state.value }</div>
    }
}

what does ::this.setState in the subscription mean in this case?

Answer 1

::this.setState=> this.setState.bind(this)
The subscribe function is passed the this.setState function with the this context.