can someone please explain what's the meaning of waypoint.below

[dmcshehan]

onEnter({previousPosition, currentPosition}){
if(previousPosition === Waypoint.below){
this.setState({
isInView : true
});
}
}`

I have this code and I'm trying to understand...
previousPosition === Waypoint.below

this part. When I log it to the console, it just prints 'below' any explanations, please? Thanks

[trotzig]

When the waypoint is below the visible portion of the page and you scroll down so that the waypoint is now visible, then onEnter will be called with previousPosition === ’below’. Waypoint.below is a constant you can use in order to avoid using the string ”below”.