NativeBridge

window.NativeBridge is the page-side bridge to Android. It is not a hidden private API. Turn it on per app, then call the methods below from the page. The same bridge is available in preview and in the exported APK when the app uses the system WebView.

Where: editor → Special settings → Native bridge (enableNativeBridge). It is on for newly created apps. Each ability has its own switch under nativeBridgeCapabilities. A method whose switch is off returns without doing the work.

GeckoView does not host this object. On that engine only the CORS-bypass / private-network httpRequest entry point is available. Clipboard, vibration, sharing, and the directory helper need the system WebView.

Call pattern

NativeBridge.showToast('Saved');
NativeBridge.vibrate(200);
const copied = NativeBridge.copyToClipboard('hello');
if (copied) NativeBridge.showToast('Copied');
NativeBridge.share('Title', 'Body', 'https://example.com');

Methods are synchronous unless the section says the result comes back through a window callback.

Capabilities

Switch	Methods it gates
Clipboard	copyToClipboard, getClipboardText
Vibration	vibrate, vibratePattern
Toast	showToast
Download	saveImageToGallery, saveVideoToGallery, downloadVideo, downloadAudio, downloadWithHeaders, saveToFile
Open external	openUrl, openApp
Device info	getDeviceInfo, getAppInfo
Security info	isDeveloperOptionsEnabled, isAdbEnabled, isDebuggable, getSecurityInfo
Network info	isNetworkAvailable, getNetworkType
Logging	log
Find in page	findInPage, findNextInPage, clearFindInPage
Orientation	setOrientation, getOrientation, lockOrientation, unlockOrientation
Brightness	setScreenBrightness
Screen wake	setKeepScreenOn
Fullscreen	enterFullscreen, exitFullscreen, isFullscreen
Print	covered by the separate print bridge
Notification	system notifications. Off by default
Google sign-in	googleSignIn. Off by default. Needs a Web client id
Folder	WtaDirectory. Off by default

Clipboard and vibration

NativeBridge.vibrate();          // 100ms
NativeBridge.vibrate(500);
NativeBridge.vibratePattern('100,200,100,200');

const ok = NativeBridge.copyToClipboard('text to copy');
const text = NativeBridge.getClipboardText(); // empty string on failure

getClipboardText needs the user to grant clipboard access when the platform asks.

Share and open

NativeBridge.share('Title', 'Body text', 'https://example.com');
NativeBridge.shareImage('https://example.com/image.jpg', 'Photo');
NativeBridge.openUrl('https://example.com');
NativeBridge.openApp('com.tencent.mm'); // returns false when the package is missing

Page-level navigator.share is a different switch: Share from the page (enableShareBridge), on by default. NativeBridge.share is this bridge.

Gallery and files

NativeBridge.saveImageToGallery('https://example.com/image.jpg', 'my_image.jpg');
NativeBridge.saveVideoToGallery('https://example.com/video.mp4', 'my_video.mp4');
NativeBridge.downloadAudio('https://example.com/audio.m4a', 'my_audio.m4a');
NativeBridge.downloadWithHeaders(
  'https://example.com/video.mp4',
  'video.mp4',
  JSON.stringify({ Referer: 'https://example.com' })
);
NativeBridge.saveToFile('note body', 'note.txt', 'text/plain');

System-download media goes into Pictures/<gallery folder> (and the matching movie or music folder). The folder name is Gallery folder on the download card. Blank stays WebToApp.

Screen, orientation, find

NativeBridge.setOrientation('landscape'); // portrait | landscape | auto
NativeBridge.setKeepScreenOn(true);
NativeBridge.setScreenBrightness(0.8);    // -1 follows the system
NativeBridge.enterFullscreen();

const state = JSON.parse(NativeBridge.findInPage('keyword'));
NativeBridge.findNextInPage(true);
NativeBridge.clearFindInPage();

Google sign-in

Off until the editor enables it and a Web client id is set. The result is not the return value.

window.NativeBridgeGoogleSignInResult = function (requestId, payload) {
  if (payload.ok) {
    // Verify payload.idToken on your server before creating a session.
  }
};
NativeBridge.googleSignIn('sign-in-' + Date.now());

payload is { ok: true, idToken, displayName, profilePictureUri, googleUserId } or { ok: false, error, message }. Error codes include DISABLED, NO_CLIENT_ID, NO_ACTIVITY, CALLER_NOT_ALLOWED, CANCELLED, CREDENTIAL_ERROR, and UNAVAILABLE.

Folder (WtaDirectory)

Off until Folder is enabled. The page must call pick() from a user gesture. The grant stays on that installed app. An exported APK is a different package and asks again. GeckoView does not include this helper.

const grant = await WtaDirectory.pick();
if (!grant.granted) return;
const entries = WtaDirectory.list('').entries;
const font = await WtaDirectory.read('fonts/MyFont.ttf');
await WtaDirectory.write('exports/image.png', pngBytes);

Method	Result
directoryInfo()	{ ok, granted, name?, writable? }
pickDirectory(requestId)	Opens the system picker. The result arrives at window.NativeBridgeDirectoryResult
listDirectory(relativePath)	{ ok, entries, truncated }. An empty path is the granted root
readDirectoryFile(relativePath, offset, length)	One chunk, at most 256 KiB, base64 in data
writeDirectoryFile(relativePath, base64, append)	Writes one chunk. append: false creates or replaces
deleteDirectoryEntry(relativePath)	Deletes a file or a child directory, never the granted root
releaseDirectory()	Drops the grant

WtaDirectory.pick, read, write, and list are the helpers injected with the capability. The object names above are the underlying NativeBridge methods.

Device and network

const device = JSON.parse(NativeBridge.getDeviceInfo());
const app = JSON.parse(NativeBridge.getAppInfo());
const security = JSON.parse(NativeBridge.getSecurityInfo());
NativeBridge.isNetworkAvailable();
NativeBridge.getNetworkType(); // "wifi" | "mobile" | "none" | "unknown"
NativeBridge.log('debug line');

Keys the page can handle

These are DOM events, not NativeBridge methods. They exist in preview and in the exported APK.

Back. Editor → back behavior → Run JavaScript. Each system Back press dispatches a cancelable wta:back on document. preventDefault() keeps the app on the page. If the page does not handle the event, Back still walks history. When that history is empty, one Back leaves the app.

document.addEventListener('wta:back', function (event) {
  if (closeMyPanel()) event.preventDefault();
});

Volume. Send volume keys to the page dispatches wta:volume. event.detail.key is VolumeUp, VolumeDown, or VolumeMute. Do not change the system volume swallows the key. Leave that switch off and the page still hears the event while the system volume changes.

document.addEventListener('wta:volume', function (event) {
  if (event.detail.key === 'VolumeUp') stepForward();
});

Downloads named by the page

An <a download="chapter.txt" href="https://..."> link, a blob: URL created from a File, and window.open of that blob keep the page's file name. The system browser already did this. The WebView download listener only sees the URL, so the shell reads the download attribute and File.name itself.