diff --git a/tsdb/fileutil/flock_js.go b/tsdb/fileutil/flock_js.go
new file mode 100644
index 000000000..c1876d4bb
--- /dev/null
+++ b/tsdb/fileutil/flock_js.go
@@ -0,0 +1,34 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build js
+// +build js
+
+package fileutil
+
+import "errors"
+
+type unixLock struct {
+}
+
+func (l *unixLock) Release() error {
+	return errors.New("unsupported")
+}
+
+func (l *unixLock) set(lock bool) error {
+	return errors.New("unsupported")
+}
+
+func newLock(fileName string) (Releaser, error) {
+	return nil, errors.New("unsupported")
+}
diff --git a/tsdb/fileutil/mmap_js.go b/tsdb/fileutil/mmap_js.go
new file mode 100644
index 000000000..0c666e8bf
--- /dev/null
+++ b/tsdb/fileutil/mmap_js.go
@@ -0,0 +1,30 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build js
+// +build js
+
+package fileutil
+
+import (
+	"errors"
+	"os"
+)
+
+func mmap(f *os.File, length int) ([]byte, error) {
+	return nil, errors.New("unsupported")
+}
+
+func munmap(b []byte) (err error) {
+	return errors.New("unsupported")
+}
diff --git a/tsdb/fileutil/mmap_unix.go b/tsdb/fileutil/mmap_unix.go
index 9365c62f7..1fd7f48ff 100644
--- a/tsdb/fileutil/mmap_unix.go
+++ b/tsdb/fileutil/mmap_unix.go
@@ -11,8 +11,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !windows && !plan9
-// +build !windows,!plan9
+//go:build !windows && !plan9 && !js
+// +build !windows,!plan9,!js
 
 package fileutil