React Router V4 Get Current Path

You will only have access to this.props.location in a Route component (as the prop is passed to the component from it).

You can get the current path with window.location.pathname outside of the Router, though it's likely that you are doing something wrong if you are accessing the path here.

For children of Router, you can access the location by wrapping it around withRouter or pass the prop downwards from a Route component.

Redux integration will also allow you to access the location from anywhere.

Fast solution
Create a variable on your function:

var currentLocation = window.location.pathname;

and then in the ul > li className={(currentLocation == '/' ? 'active' : '')}

it worked for mee and is a quick solution.