wbn

v0.0.9

Published

2 years ago

Generator and parser for the application/webbundle format, defined in draft-ietf-wpack-bundled-responses-01.

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google-wombot

ksakamoto

web bundles webpackage bundled exchanges

Web Bundles

This is a Node.js module for serializing and parsing the application/webbundle format defined in the Web Bundles draft spec.

Installation

Using npm:

npm install wbn

Usage

Please be aware that the API is not yet stable and is subject to change any time.

Creating a Bundle:

import * as fs from 'fs';
import * as wbn from 'wbn';

const builder = new wbn.BundleBuilder();
builder.addExchange(
  'https://example.com/', // URL
  200, // response code
  { 'Content-Type': 'text/html' }, // response headers
  '<html>Hello, Web Bundle!</html>' // response body (string or Uint8Array)
);
builder.setPrimaryURL('https://example.com/'); // entry point URL

fs.writeFileSync('out.wbn', builder.createBundle());

Reading a Bundle:

import * as fs from 'fs';
import * as wbn from 'wbn';

const buf = fs.readFileSync('out.wbn');
const bundle = new wbn.Bundle(buf);
const exchanges = [];
for (const url of bundle.urls) {
  const resp = bundle.getResponse(url);
  exchanges.push({
    url,
    status: resp.status,
    headers: resp.headers,
    body: new TextDecoder('utf-8').decode(resp.body),
  });
}
console.log(
  JSON.stringify(
    {
      version: bundle.version, // format version
      exchanges,
    },
    null,
    2
  )
);

CLI

This package also includes wbn command which lets you build a web bundle from a local directory. For example, if you have all the necessary files for https://example.com/ in static/ directory, run the following command:

$ wbn --dir static \
      --baseURL https://example.com/ \
      --output out.wbn

Run wbn --help for full options.

Note: currently this CLI only covers a subset of the functionality offered by gen-bundle Go tool.

Backwards compatibility

This module supports creating and parsing Web Bundles that follow different draft versions of the format specification. In particular:

version b2 follows the latest version of the Web Bundles spec (default)
version b1 follows the previous version of the Web Bundles spec

To create a new bundle with the b1 format, pass the version value to the constructor:

const builder = (new wbn.BundleBuilder('b1'))
  .setPrimaryURL('https://example.com/')
  .setManifestURL('https://example.com/manifest.json')
  .addExchange(...);

fs.writeFileSync('out_b1.wbn', builder.createBundle());

Likewise, the wbn command can optionally take a --formatVersion b1 parameter when creating a new Web Bundle.

This module also takes care of selecting the right format version automatically when reading a bundle. Check the property bundle.version to know the decoded bundle's format version.

Using Bundles

Generated bundles can be opened with web browsers supporting web bundles.

Chrome (79+) experimentally supports navigation to Web Bundles with some limitations. See this document for more details.

Chrome (104+) supports <script type=webbundle>.

Release Notes

0.0.9

Add support for overriding headers.

0.0.8

Now wbn package provides both ES modules and CommonJS exports.
Dependency on the Node.js API has been removed from the wbn module, making it easier to use the module in browsers.

0.0.7

Now BundleBuilder accepts relative resource URLs. Relative URLs can be used in <script type=webbundle> where relative URLs are resolved using the bundle's URL as base URL.

0.0.6

Now BundleBuilder generates bundles of format b2 by default. See Backwards compatibility section above.

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