Native Bridge is a lightweight and efficient bridge between webview and native app. It's primary use case is to share state between native apps and javascript in webviews.


1601.1.93 years ago4 years agoMinified + gzip package size for @nrk/nativebridge in KB



Native Bridge is a lightweight and efficient bridge between webview and native app. It's primary use case is to share state between native apps and javascript in webviews.


Android iOS
Tested on Android 4.4.4+ iOS 10.2+


Used as a producer/consumer-interface for passing messages to/from native app (iOs/Android). Following an EventEmitter interface (on/once/off/emit). In addition an RPC-interface makes calling native methods a breeze.

EMIT - send to native:
nativebridge.emit('test', { foo: 'bar' })  // Emit 'test' event with data (must be object) to native
ON/ONCE - receives from native:
nativebridge.on('test', (data) => {})       // Bind handler to 'test' event emitted from native
nativebridge.once('test', (data) => {})     // Bind handler to 'test' (one time only) event emitted from native
OFF: - remove handler(s)
nativebridge.off('test')                    // Unbind all handlers for 'test' event
nativebridge.off('test', (data) => {})      // Unbind specific handler for 'test' event
RPC: - make call to native app using topic as contract

Make a remote procedure call (RPC) using nativebridge interfaces as described above. Resolves with data on completion, or rejects with error details from the app (or timeout).

// Auto-bind handlers (once/emit) to complete an RPC-call to native
  topic: 'test',                             // using 'test' as event
  data: {},                                 // with data (args)
  resolve: (data) => {},                    // using callback on success
  reject: (err) => {},                      // or rejection on error
  timeout: 1000                             // with a timeout threshold


npm install @nrk/nativebridge --save
import nativebridge from '@nrk/nativebridge'
<script src="https://static.nrk.no/nativebridge/X.X.X/nativebridge.min.js"></script>
<!-- window.nativebridge is now defined -->
require(['https://static.nrk.no/nativebridge/X.X.X/nativebridge.min.js'], function(nativebridge) {
  /* code here */

How does it work


A data object is sent using topic as topic to an exposed method on either:

  • Android:
    window.webkit.messageHandlers.nativebridgeiOS.postMessage({topic: "test", data: {foo: "bar"}})
  • iOS:
    window.NativeBridgeAndroid.send(JSON.stringify({topic: "test", data: {foo: "bar"}}))
Android/iOS handler

Topic-handlers are mapped to native functions, using data-object as an argument e.g topicHandler({topic: "test", data: {foo: "bar"}}). The app injects a js-snippet to dispatch a message back to the webpage using CustomEvents:

window.dispatchEvent(new CustomEvent('nativebridge', { detail: {topic, data} }))

The CustomEvent dispatched from the native app is ran using attached callback-handlers on the given topic.

Error handling

If an error occurs in the native app, an Error object will be rejected, eg.

err.message = '[{message: "no handler available", errorCode: 100}]'

The RPC-method is made to simplify on/off/emit-logistics. In addition it supports a timeout, which will throw an error if timeout is reached:

err.message = 'RPC for test using {} timed out after 1000ms'

Local development (web)

First clone @nrk/nativebridge and install its dependencies:

git clone git@github.com:nrkno/nativebridge.git
cd nativebridge
npm install && npm start

Building and committing

After having applied changes, remember to build before pushing the changes upstream.

git checkout -b feature/my-changes
# update the source code
npm run build
git commit -am "Add my changes"
git push origin feature/my-changes
# then make a PR to the master branch,
# and assign another developer to review your code

NOTE! Please also make sure to keep commits small and clean (that the commit message actually refers to the updated files).
Stylistically, make sure the commit message is Capitalized and starts with a verb in the present tense (for example Add minification support).

If you find any bugs or have a feature request, please open an issue on github!

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