ecmascript 6 - ReactJS - props or propTypes? -

when i'm reading props open source, see use of props , proptypes declare properties obtained parent. difference between two? 1 should used?

for example:

props source code

export default class app extends component {   props: {     children: children   };    render() {     return (       <div>         {this.props.children}       </div>     );   } } 

proptypes source code

export default class board extends component {   static proptypes = {     getlists: proptypes.func.isrequired,     movecard: proptypes.func.isrequired,     movelist: proptypes.func.isrequired,     lists: proptypes.array.isrequired,   }   ... } 

props actual properties sent react class. proptypes used define properties class supposed receive. should use both more props

nice thing proptypes helps ensure correct type sent every property since define should be... meaning receive console warning saying invalid prop type passed component. more proptypes

dont forget @ stack overflows documentation!