Trouble serving JavaScript and asset files with Gorilla Mux in Golang

Question

I have file system like this:

  -- api
     -> api.go
  -- styles
    -> style1.css
    -> style2.css
    -> ...
  -- scripts
    -> script1.js
    -> script2.js
    -> ...
  -- static
    -> page1.html
    -> page2.html
    -> ...
  -- assets
    -> image1.png
    -> image2.png
    -> ...
  -- main.go

In api.go file I set my Gorilla mux server like this, (got code from this Golang Gorilla mux with http.FileServer returning 404) :

func (api *APIServer) Run() {
    router := mux.NewRouter()


    router.PathPrefix("/styles/").Handler(http.StripPrefix("/styles/",
        http.FileServer(http.Dir("styles"))))

    router.PathPrefix("/").Handler(http.StripPrefix("/",
        http.FileServer(http.Dir("static"))))

    router.PathPrefix("/scripts/").Handler(http.StripPrefix("/scripts/",
        http.FileServer(http.Dir("scripts"))))

    router.PathPrefix("/assets/").Handler(http.StripPrefix("/assets/",
        http.FileServer(http.Dir("assets"))))


    if err := http.ListenAndServe(api.listenAddr, router); err != nil {
        log.Printf("error starting server %s", err.Error())
    }
    fmt.Println("server start running")
}

html file:

<link rel="stylesheet" type="text/css" href="styles\login.css" />
<script src="scripts\login.js"></script>
<img
    id="img-show"
    src="assets\bin.png"
    alt=""
    width="25px"
/>

The browser sees only html (static) and css (styles), but does not see scripts and assets, despite the fact that everything is done identically to the first two. Error:

(Golang Gorilla mux with http.FileServer returning 404) Both options only helped for html and css files, changing the paths also didn't give any results.

Answer 1

Your problem is caused by the "/" handler, which matches "/assets" and "/scripts", and is declared before those routes. See here how gorilla/mux matches routes

If you rearrange the routes order, this problem will be gone:

    router.PathPrefix("/styles/").Handler(http.StripPrefix("/styles/",
        http.FileServer(http.Dir("styles"))))

    router.PathPrefix("/scripts/").Handler(http.StripPrefix("/scripts/",
        http.FileServer(http.Dir("scripts"))))

    router.PathPrefix("/assets/").Handler(http.StripPrefix("/assets/",
        http.FileServer(http.Dir("assets"))))

    router.PathPrefix("/").Handler(http.StripPrefix("/",
        http.FileServer(http.Dir("static"))))