React Router v3 provides onEnter, onUpdate, and onLeave methods. These were essentially recreating React's lifecycle methods.
With v4, you should use the lifecycle methods of the component rendered by a <Route>. Instead of onEnter, you would use componentDidMount or componentWillMount. Where you would use onUpdate, you can use componentDidUpdate or componentWillUpdate (or possibly componentWillReceiveProps). onLeave can be replaced with componentWillUnmount.
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React Router v3 provides onEnter, onUpdate, and onLeave methods. These were essentially recreating React's lifecycle methods.
With v4, you should use the lifecycle methods of the component rendered by a <Route>. Instead of onEnter, you would use componentDidMount or componentWillMount. Where you would use onUpdate, you can use componentDidUpdate or componentWillUpdate (or possibly componentWillReceiveProps). onLeave can be replaced with componentWillUnmount.