Custom Error Pages in Go

custom404.go

// Source: https://stackoverflow.com/questions/9996767/showing-custom-404-error-page-with-standard-http-package

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", homeHandler)
    http.HandleFunc("/smth/", smthHandler)
    http.ListenAndServe(":12345", nil)
}

func homeHandler(w http.ResponseWriter, r *http.Request) {
    if r.URL.Path != "/" {
        errorHandler(w, r, http.StatusNotFound)
        return
    }
    fmt.Fprint(w, "welcome home")
}

func smthHandler(w http.ResponseWriter, r *http.Request) {
    if r.URL.Path != "/smth/" {
        errorHandler(w, r, http.StatusNotFound)
        return
    }
    fmt.Fprint(w, "welcome smth")
}

func errorHandler(w http.ResponseWriter, r *http.Request, status int) {
    w.WriteHeader(status)
    if status == http.StatusNotFound {
        fmt.Fprint(w, "custom 404")
    }
}