Why does react-router treat a regex `path` correctly, but throws an error at the same time?

Question

I have a component that I want to be displayed on all the paths except for root path. So instead of providing all the paths to the Route component, I wrote this:

<Route exact path={/^\/.+$/} component={() =>
  <div><img src="../../../assets/AndreyBogdanov2.jpg" className="me" /></div>
} />

That regex matches all the strings that have any character after the slash in the beginning. And it works as expected, however, in the console I see an error:

Warning: Failed prop type: Invalid prop `path` of type `regexp` supplied to `Route`, expected `string`.
    in Route (created by App)
    in App
    in Router (created by BrowserRouter)
    in BrowserRouter

Not that I'm complaining, but I would like to know, how come it works?

In the docs for the path prop it says that it needs to be any URL that path-to-regexp understands, and in the path-to-regexp's docs, it says that regex is a valid parameter. So basically, it's the component's PropTypes that throws the error when it encounters something other than a string.

Answer 1

It is because it can only accept a string value. You also need to insert something that path-to-regexp can read as described in React Router Training. You can look for how to write valid regexes in their repository here.