React PropTypes & Flow types cheat sheetQuick post that documents the various quirks of `propTypes`. The React `propTypes` semantics differ from the ones from Flow and can cause subtle bugs. Here’s a handy cheat sheet. PropTypespropTypes: { // field required, must be number and NOT `null` NOR `undefined` foo: PropTypes.number.isRequired } propTypes: { // field can be omitted; if provided, can be number OR `null` OR `undefined` foo: Prop
