web-push

Why

Web push requires that push messages triggered from a backend be done via the Web Push Protocol and if you want to send data with your push message, you must also encrypt that data according to the Message Encryption for Web Push spec.

This module makes it easy to send messages and will also handle legacy support for browsers relying on GCM for message sending / delivery.

Install

Installation is simple, just install via npm.

npm install web-push --save

Usage

The common use case for this library is an application server using a GCM API key and VAPID keys.

const webpush = require('web-push');

// VAPID keys should only be generated only once.
const vapidKeys = webpush.generateVAPIDKeys();

webpush.setGCMAPIKey('<Your GCM API Key Here>');
webpush.setVapidDetails(
  'mailto:example@yourdomain.org',
  vapidKeys.publicKey,
  vapidKeys.privateKey
);

// This is the same output of calling JSON.stringify on a PushSubscription
const pushSubscription = {
  endpoint: '.....',
  keys: {
    auth: '.....',
    p256dh: '.....'
  }
};

webpush.sendNotification(pushSubscription, 'Your Push Payload Text');

Using VAPID Key for applicationServerKey

When using your VAPID key in your web app, you'll need to convert the URL safe base64 string to a Uint8Array to pass into the subscribe call, which you can do like so:

function urlBase64ToUint8Array(base64String) {
  const padding = '='.repeat((4 - base64String.length % 4) % 4);
  const base64 = (base64String + padding)
    .replace(/\-/g, '+')
    .replace(/_/g, '/');

  const rawData = window.atob(base64);
  const outputArray = new Uint8Array(rawData.length);

  for (let i = 0; i < rawData.length; ++i) {
    outputArray[i] = rawData.charCodeAt(i);
  }
  return outputArray;
}

const vapidPublicKey = '<Your Public Key from generateVAPIDKeys()>';
const convertedVapidKey = urlBase64ToUint8Array(vapidPublicKey);

registration.pushManager.subscribe({
  userVisibleOnly: true,
  applicationServerKey: convertedVapidKey
});

Command Line

You can install web-push globally and use it for sending notifications and / or generating VAPID keys.

Install like so:

npm install web-push -g

Then you can run the following commands:

Usage:

  web-push send-notification --endpoint=<url> [--key=<browser key>] [--auth=<auth secret>] [--payload=<message>] [--encoding=<aesgcm | aes128gcm>] [--ttl=<seconds>] [--vapid-subject=<vapid subject>] [--vapid-pubkey=<public key url base64>] [--vapid-pvtkey=<private key url base64>] [--gcm-api-key=<api key>]

  web-push generate-vapid-keys [--json]

API Reference

sendNotification(pushSubscription, payload, options)

const pushSubscription = {
  endpoint: '< Push Subscription URL >',
  keys: {
    p256dh: '< User Public Encryption Key >',
    auth: '< User Auth Secret >'
  }
};

const payload = '< Push Payload String >';

const options = {
  gcmAPIKey: '< GCM API Key >',
  vapidDetails: {
    subject: '< \'mailto\' Address or URL >',
    publicKey: '< URL Safe Base64 Encoded Public Key >',
    privateKey: '< URL Safe Base64 Encoded Private Key >'
  },
  TTL: <Number>,
  headers: {
    '< header name >': '< header value >'
  },
  contentEncoding: '< Encoding type, e.g.: aesgcm or aes128gcm >'
}

webpush.sendNotification(
  pushSubscription,
  payload,
  options
);

Note: sendNotification() you don't need to define a payload, and this method will work without a GCM API Key and / or VAPID keys if the push service supports it.

Input

Push Subscription

The first argument must be an object containing the details for a push subscription.

The expected format is the same output as JSON.stringify'ing a PushSubscription in the browser.

Payload

The payload is optional, but if set, will be the data sent with a push message.

This must be either a string or a node Buffer.

Note: In order to encrypt the payload, the pushSubscription must have a keys object with p256dh and auth values.

Options

Options is an optional argument that if defined should be an object containing any of the following values defined, although none of them are required.

gcmAPIKey can be a GCM API key to be used for this request and this request only. This overrides any API key set via setGCMAPIKey().
vapidDetails should be an object with subject, publicKey and privateKey values defined. These values should follow the VAPID Spec.
TTL is a value in seconds that describes how long a push message is retained by the push service (by default, four weeks).
headers is an object with all the extra headers you want to add to the request.
contentEncoding is the type of push encoding to use (e.g. 'aesgcm', by default, or 'aes128gcm').

Returns

A promise that resolves if the notification was sent successfully with details of the request, otherwise it rejects.

In both cases, resolving or rejecting, you'll be able to access the following values on the returned object or error.

statusCode, the status code of the response from the push service;
headers, the headers of the response from the push service;
body, the body of the response from the push service.

generateVAPIDKeys()

const vapidKeys = webpush.generateVAPIDKeys();

// Prints 2 URL Safe Base64 Encoded Strings
console.log(vapidKeys.publicKey, vapidKeys.privateKey);

Input

None.

Returns

Returns an object with publicKey and privateKey values which are URL Safe Base64 encoded strings.

Note: You should create these keys once, store them and use them for all future messages you send.

setGCMAPIKey(apiKey)

webpush.setGCMAPIKey('Your GCM API Key');

Input

This method expects the GCM API key that is linked to the gcm_sender_id in your web app manifest.

You can use a GCM API Key from the Google Developer Console or the Cloud Messaging tab under a Firebase Project.

Returns

None.

encrypt(userPublicKey, userAuth, payload, contentEncoding)

const pushSubscription = {
  endpoint: 'https://....',
  keys: {
    p256dh: '.....',
    auth: '.....'
  }
};
webPush.encrypt(
  pushSubscription.keys.p256dh,
  pushSubscription.keys.auth,
  'My Payload',
  'aes128gcm'
)
.then(encryptionDetails => {

});

Encrypts the payload according to the Message Encryption for Web Push standard.

(sendNotification will automatically encrypt the payload for you, so if you use sendNotification you don't need to worry about it).

Input

The encrypt() method expects the following input:

userPublicKey: the public key of the receiver (from the browser).
userAuth: the auth secret of the receiver (from the browser).
payload: the message to attach to the notification.
contentEncoding: the type of content encoding to use (e.g. aesgcm or aes128gcm).

Returns

This method returns an object with the following fields:

localPublicKey: The public key matched the private key used during encryption.
salt: A string representing the salt used to encrypt the payload.
cipherText: The encrypted payload as a Buffer.

getVapidHeaders(audience, subject, publicKey, privateKey, contentEncoding, expiration)

const parsedUrl = url.parse(subscription.endpoint);
const audience = parsedUrl.protocol + '//' +
  parsedUrl.hostname;

const vapidHeaders = vapidHelper.getVapidHeaders(
  audience,
  'mailto: example@web-push-node.org',
  vapidDetails.publicKey,
  vapidDetails.privateKey,
  'aes128gcm'
);

The getVapidHeaders() method will take in the values needed to create an Authorization and Crypto-Key header.

Input

The getVapidHeaders() method expects the following input:

audience: the origin of the push service.
subject: the mailto or URL for your application.
publicKey: the VAPID public key.
privateKey: the VAPID private key.
contentEncoding: the type of content encoding to use (e.g. aesgcm or aes128gcm).

Returns

This method returns an object with the following fields:

localPublicKey: The public key matched the private key used during encryption.
salt: A string representing the salt used to encrypt the payload.
cipherText: The encrypted payload as a Buffer.

generateRequestDetails(pushSubscription, payload, options)

const pushSubscription = {
  endpoint: '< Push Subscription URL >';
  keys: {
    p256dh: '< User Public Encryption Key >',
    auth: '< User Auth Secret >'
  }
};

const payload = '< Push Payload String >';

const options = {
  gcmAPIKey: '< GCM API Key >',
  vapidDetails: {
    subject: '< \'mailto\' Address or URL >',
    publicKey: '< URL Safe Base64 Encoded Public Key >',
    privateKey: '< URL Safe Base64 Encoded Private Key >',
  }
  TTL: <Number>,
  headers: {
    '< header name >': '< header value >'
  },
  contentEncoding: '< Encoding type, e.g.: aesgcm or aes128gcm >'
}

try {
  const details = webpush.generateRequestDetails(
    pushSubscription,
    payload,
    options
  );
} catch (err) {
  console.error(err);
}

Note: When calling generateRequestDetails() the payload argument does not need to be defined, passing in null will return no body and exclude any unnecessary headers. Headers related to the GCM API Key and / or VAPID keys will be included if supplied and required.

Input

Push Subscription

The first argument must be an object containing the details for a push subscription.

The expected format is the same output as JSON.stringify'ing a PushSubscription in the browser.

Payload

The payload is optional, but if set, will be encrypted and a Buffer will be returned via the payload parameter.

This argument must be either a string or a node Buffer.

Note: In order to encrypt the payload, the pushSubscription must have a keys object with p256dh and auth values.

Options

Options is an optional argument that if defined should be an object containing any of the following values defined, although none of them are required.

gcmAPIKey can be a GCM API key to be used for this request and this request only. This overrides any API key set via setGCMAPIKey().
vapidDetails should be an object with subject, publicKey and privateKey values defined. These values should follow the VAPID Spec.
TTL is a value in seconds that describes how long a push message is retained by the push service (by default, four weeks).
headers is an object with all the extra headers you want to add to the request.
contentEncoding is the type of push encoding to use (e.g. 'aesgcm', by default, or 'aes128gcm').

Returns

An object containing all the details needed to make a network request, the object will contain:

endpoint, the URL to send the request to;
method, this will be 'POST';
headers, the headers to add to the request;
body, the body of the request (As a Node Buffer).

Browser Support

Browser	Push without Payload	Push with Payload	VAPID	Notes
Chrome	✓ v42+	✓ v50+	✓ v52+	In v51 and less, the `gcm_sender_id` is needed to get a push subscription.
Edge	✗	✗	✗
Firefox	✓ v44+	✓ v44+	✓ v46+
Opera	✓ v39+ *	✓ v39+ *	✗	* Opera supports push on Android but not on desktop. The `gcm_sender_id` is needed to get a push subscription.
Safari	✗	✗	✗
Samsung Internet Browser	✓ v4.0.10-53+	✓ v5.0.30-40+	✗	The `gcm_sender_id` is needed to get a push subscription.

Help

Service Worker Cookbook

The Service Worker Cookbook is full of Web Push examples using this library.

Running tests

Prerequisites:

Java JDK or JRE (http://www.oracle.com/technetwork/java/javase/downloads/index.html)

To run tests:

npm test

License

aliams/web-push

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