How to reveal a React component on scroll

Question

I've created a React component for a fixed nav that I would like to remain hidden, until I scroll past a certain point on the page, then slides into view. Medium has a header similar to what I'm describing.

This is a relatively trivial task in jQuery, with scrollmagic or waypoints but is there an idiomatic way of accomplishing this with React and vanilla JS?

Answer 1

React Way with vanilla JS jsfiddle;

don't forget to remove EventListener. In this example component will render if only it is neccessary

class TopBar extends React.Component {
    state = { isHide: false };

    hideBar = () => {
       const { isHide } = this.state

       window.scrollY > this.prev ?
       !isHide && this.setState({ isHide: true })
       :
       isHide && this.setState({ isHide: false });

       this.prev = window.scrollY;
    }

    componentDidMount(){
        window.addEventListener('scroll', this.hideBar);
    }

    componentWillUnmount(){
         window.removeEventListener('scroll', this.hideBar);
    }

    render(){
        const classHide = this.state.isHide ? 'hide' : '';
        return <div className={`topbar ${classHide}`}>topbar</div>;
    }
}

Answer 2

You could use a component such as react-headroom to do the heavy lifting for you. Or, you can still use waypoints in React, setting it up in the componentDidMount lifecycle method and removing it using componentWillUnmount.