// Copyright 2021 The Go Authors. All rights reserved.// Use of this source code is governed by a BSD-style// license that can be found in the LICENSE file.//go:build jspackage fdtest
import("syscall")// Exists returns true if fd is a valid file descriptor.funcExists(fd uintptr)bool{var s syscall.Stat_t
err := syscall.Fstat(int(fd), &s)return err != syscall.EBADF
}