feat: add net.online / net.isOnline() (electron#21004)

docs/api/net.md

@@ -8,7 +8,7 @@ The `net` module is a client-side API for issuing HTTP(S) requests. It is
 similar to the [HTTP](https://nodejs.org/api/http.html) and
 [HTTPS](https://nodejs.org/api/https.html) modules of Node.js but uses
 Chromium's native networking library instead of the Node.js implementation,
-offering better support for web proxies.
+offering better support for web proxies. It also supports checking network status.
 
 The following is a non-exhaustive list of why you may consider using the `net`
 module instead of the native Node.js modules:
@@ -62,3 +62,25 @@ Creates a [`ClientRequest`](./client-request.md) instance using the provided
 `options` which are directly forwarded to the `ClientRequest` constructor.
 The `net.request` method would be used to issue both secure and insecure HTTP
 requests according to the specified protocol scheme in the `options` object.
+
+### `net.isOnline()`
+
+Returns `Boolean` - Whether there is currently internet connection.
+
+A return value of `false` is a pretty strong indicator that the user
+won't be able to connect to remote sites. However, a return value of
+`true` is inconclusive; even if some link is up, it is uncertain
+whether a particular connection attempt to a particular remote site
+will be successful.
+
+## Properties
+
+### `net.online` _Readonly_
+
+A `Boolean` property. Whether there is currently internet connection.
+
+A return value of `false` is a pretty strong indicator that the user
+won't be able to connect to remote sites. However, a return value of
+`true` is inconclusive; even if some link is up, it is uncertain
+whether a particular connection attempt to a particular remote site
+will be successful.

lib/browser/api/net.ts

@@ -4,6 +4,7 @@ import { app } from 'electron/main';
 import type { ClientRequestConstructorOptions, UploadProgress } from 'electron/main';
 
 const {
+  isOnline,
   isValidHeaderName,
   isValidHeaderValue,
   createURLLoader
@@ -516,3 +517,9 @@ export class ClientRequest extends Writable implements Electron.ClientRequest {
 export function request (options: ClientRequestConstructorOptions | string, callback?: (message: IncomingMessage) => void) {
   return new ClientRequest(options, callback);
 }
+
+exports.isOnline = isOnline;
+
+Object.defineProperty(exports, 'online', {
+  get: () => isOnline()
+});

shell/browser/api/electron_api_net.cc

@@ -5,6 +5,7 @@
 #include <string>
 
 #include "gin/handle.h"
+#include "net/base/network_change_notifier.h"
 #include "services/network/public/cpp/features.h"
 #include "shell/browser/api/electron_api_url_loader.h"
 #include "shell/common/gin_helper/dictionary.h"
@@ -14,6 +15,10 @@
 
 namespace {
 
+bool IsOnline() {
+  return !net::NetworkChangeNotifier::IsOffline();
+}
+
 bool IsValidHeaderName(std::string header_name) {
   return net::HttpUtil::IsValidHeaderName(header_name);
 }
@@ -31,6 +36,7 @@ void Initialize(v8::Local<v8::Object> exports,
   v8::Isolate* isolate = context->GetIsolate();
 
   gin_helper::Dictionary dict(isolate, exports);
+  dict.SetMethod("isOnline", &IsOnline);
   dict.SetMethod("isValidHeaderName", &IsValidHeaderName);
   dict.SetMethod("isValidHeaderValue", &IsValidHeaderValue);
   dict.SetMethod("createURLLoader", &SimpleURLLoaderWrapper::Create);

spec-main/api-net-spec.ts

@@ -1500,6 +1500,16 @@ describe('net module', () => {
     });
   });
 
+  describe('net.isOnline', () => {
+    it('getter returns boolean', () => {
+      expect(net.isOnline()).to.be.a('boolean');
+    });
+
+    it('property returns boolean', () => {
+      expect(net.online).to.be.a('boolean');
+    });
+  });
+
   describe('Stability and performance', () => {
     it('should free unreferenced, never-started request objects without crash', (done) => {
       net.request('https://test');

typings/internal-ambient.d.ts

@@ -194,6 +194,7 @@ declare namespace NodeJS {
       createPair(): { port1: Electron.MessagePortMain, port2: Electron.MessagePortMain };
     };
     _linkedBinding(name: 'electron_browser_net'): {
+      isOnline(): boolean;
       isValidHeaderName: (headerName: string) => boolean;
       isValidHeaderValue: (headerValue: string) => boolean;
       Net: any;