mime: incorrect mime-type for .js files on windows 10 (text/plain instead of application/javascript) #32350
Description
What version of Go are you using (go version)?
$ go version go version go1.12.5 windows/amd64
Does this issue reproduce with the latest release?
Yes
What operating system and processor architecture are you using (go env)?
go env Output
$ go env set GOARCH=amd64 set GOBIN= set GOCACHE=C:\Users\kjk\AppData\Local\go-build set GOEXE=.exe set GOFLAGS= set GOHOSTARCH=amd64 set GOHOSTOS=windows set GOOS=windows set GOPATH=C:\Users\kjk\go set GOPROXY= set GORACE= set GOROOT=C:\Go set GOTMPDIR= set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64 set GCCGO=gccgo set CC=gcc set CXX=g++ set CGO_ENABLED=1 set GOMOD=C:\Users\kjk\src\apps\offdocs\go.mod set CGO_CFLAGS=-g -O2 set CGO_CPPFLAGS= set CGO_CXXFLAGS=-g -O2 set CGO_FFLAGS=-g -O2 set CGO_LDFLAGS=-g -O2 set PKG_CONFIG=pkg-config set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\kjk\AppData\Local\Temp\go-build840166758=/tmp/go-build -gno-record-gcc-switches
What did you do?
Consider this program:
package main
import (
"fmt"
"mime"
)
func main() {
ct := mime.TypeByExtension(".js")
fmt.Printf("ct: %s\n", ct)
}
https://play.golang.org/p/JTVjWc9xMDE
What did you expect to see?
Mime-type for .js files should be application/javascript on all platforms.
What did you see instead?
On Linux it returns ct: application/javascript
On my latest Windows 10 it returns ct: text/plain; charset=utf-8
This also affects Content-Type returned by http.ServeFile() for .js files.
This is because in src\mime\type.go:
func initMime() {
if fn := testInitMime; fn != nil {
fn()
} else {
setMimeTypes(builtinTypesLower, builtinTypesLower)
osInitMime()
}
}On Windows osInitMime() reads info for additional extensions from registry and over-writes mime-type for .js files.
Note: it's possible this won't repro on every version on Windows.
Reversing the initialization order should fix it:
osInitMime()
setMimeTypes(builtinTypesLower, builtinTypesLower)