remove net when targeting JS

node.go

@@ -5,16 +5,14 @@
 package uuid
 
 import (
-	"net"
 	"sync"
 )
 
 var (
-	nodeMu     sync.Mutex
-	interfaces []net.Interface // cached list of interfaces
-	ifname     string          // name of interface being used
-	nodeID     [6]byte         // hardware for version 1 UUIDs
-	zeroID     [6]byte         // nodeID with only 0's
+	nodeMu sync.Mutex
+	ifname string  // name of interface being used
+	nodeID [6]byte // hardware for version 1 UUIDs
+	zeroID [6]byte // nodeID with only 0's
 )
 
 // NodeInterface returns the name of the interface from which the NodeID was
@@ -39,20 +37,12 @@ func SetNodeInterface(name string) bool {
 }
 
 func setNodeInterface(name string) bool {
-	if interfaces == nil {
-		var err error
-		interfaces, err = net.Interfaces()
-		if err != nil && name != "" {
-			return false
-		}
-	}
 
-	for _, ifs := range interfaces {
-		if len(ifs.HardwareAddr) >= 6 && (name == "" || name == ifs.Name) {
-			copy(nodeID[:], ifs.HardwareAddr)
-			ifname = ifs.Name
-			return true
-		}
+	iname, addr := getHardwareInterface(name) // null implementation for js
+	if iname != "" && addr != nil {
+		ifname = iname
+		copy(nodeID[:], addr)
+		return true
 	}
 
 	// We found no interfaces with a valid hardware address.  If name

node_js.go

@@ -0,0 +1,12 @@
+// Copyright 2017 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build js
+
+package uuid
+
+// getHardwareInterface returns nil values for the JS version of the code.
+// This remvoves the "net" dependency, because it is not used in the browser.
+// Using the "net" library inflates the size of the transpiled JS code by 673k bytes.
+func getHardwareInterface(name string) (string, []byte) { return "", nil }

node_net.go

@@ -0,0 +1,33 @@
+// Copyright 2017 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !js
+
+package uuid
+
+import "net"
+
+var interfaces []net.Interface // cached list of interfaces
+
+// getHardwareInterface returns the name and hardware address of interface name.
+// If name is "" then the name and hardware address of one of the system's
+// interfaces is returned.  If no interfaces are found (name does not exist or
+// there are no interfaces) then "", nil is returned.
+//
+// Only addresses of at least 6 bytes are returned.
+func getHardwareInterface(name string) (string, []byte) {
+	if interfaces == nil {
+		var err error
+		interfaces, err = net.Interfaces()
+		if err != nil {
+			return "", nil
+		}
+	}
+	for _, ifs := range interfaces {
+		if len(ifs.HardwareAddr) >= 6 && (name == "" || name == ifs.Name) {
+			return ifs.Name, ifs.HardwareAddr
+		}
+	}
+	return "", nil
+}

uuid_test.go

@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"fmt"
 	"os"
+	"runtime"
 	"strings"
 	"testing"
 	"time"
@@ -321,8 +322,10 @@ func TestNode(t *testing.T) {
 	if !SetNodeInterface("") {
 		t.Error("SetNodeInterface failed")
 	}
-	if ni := NodeInterface(); ni == "" {
-		t.Error("NodeInterface returned an empty string")
+	if runtime.GOARCH != "js" {
+		if ni := NodeInterface(); ni == "" {
+			t.Error("NodeInterface returned an empty string")
+		}
 	}
 
 	ni := NodeID()
@@ -391,8 +394,10 @@ func TestNodeID(t *testing.T) {
 	nid := []byte{1, 2, 3, 4, 5, 6}
 	SetNodeInterface("")
 	s := NodeInterface()
-	if s == "" || s == "user" {
-		t.Errorf("NodeInterface %q after SetInterface", s)
+	if runtime.GOARCH != "js" {
+		if s == "" || s == "user" {
+			t.Errorf("NodeInterface %q after SetInterface", s)
+		}
 	}
 	node1 := NodeID()
 	if node1 == nil {