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webtamp Build Status npm

webtamp is bundler for assets. It is inspired by webpack, and meant to be a companion to JS-driven bundlers like webpack.

You can do a lot of cool and useful things with webpack and its plugin community. However, there are a number of things that either can't be done at all, or can be done poorly and with difficulty by plugin that hack webpack in a way it wasn't meant for. The webpack authors are very clear about the scope and boundaries of webpack and fair enough.

webtamp exists to address the gap. It does all the things I need to do for my webapp's assets, after I've used webpack.



  • Anything can be a top-level asset. No JS loader required or generated.
  • Dynamic filenames with hashing options.
  • Easy to integrate non-module based libraries, including those that expect relative assets with precise names.
  • CDNs supported directly.
    • Integrity can be specified manually.
    • Integrity can be calculated from local files.
  • Assets can be optional and will only be included when referenced (with transitivity).
  • Generate URL manifests.
    • Formats can be JSON and Scala.
    • Configure what is/isn't included in the manifest, and the names of entries.
    • Includes inlined assets.
  • Inliner plugin to inline assets (usually with size < n) into data: URIs.
  • HTML integration
    • Replaces <require ... > with tags that load the asset, and all of its dependencies in order.
    • Replaces attributes like webtamp://manifest/welcomeSvg with real URLs.
    • Loads from CDN and locally-served assets alike.
    • Any missing assets fail fast.
  • Plugin system.


  1. Install.

    npm install --save-dev webtamp
  2. Create a config file, default name is webtamp.config.js.

    For details on all available options, see doc/config.sample.js.

    A good starting point with commonly-used would be:

    const webtamp = require('webtamp');
    module.exports = {
      output: {
        dir: 'dist',
        name: '[name]-[hash].[ext]',
      assets: {
        // mandatory assets go here
      optional: {
        // optional assets go here
      plugins: [
  3. Run it.


    Or if you named your config file differently:

    ./node_modules/.bin/webtamp --config <file>

    There's also a dry-run mode so no one gets hurt:

    ./node_modules/.bin/webtamp [--config <file>] --dryrun


  • webtamp.plugins.Modify.content - Modify certain files' content.
  • webtamp.plugins.Modify.rename - Modify rename certain files.
  • webtamp.plugins.Modify.{stateful,stateless} - Modify files' names and content with more control.
  • - For files that given criteria, exclude from output and replace with a data URI.
  • webtamp.plugins.Html.replace - Replace <require> tags and webtamp:// URIs with real asset tags/links. Missing assets will fail the build.
  • webtamp.plugins.Html.minify - Minify HTML.
  • webtamp.plugins.Manifest.extractCss - Extract URLs from CSS and add those to the manifest.
  • webtamp.plugins.Manifest.generate.scala - Generate the asset manifest in Scala/Scala.JS.


This will demonstrate a number of features. Not all but enough to be useful.

Say you have a tree of files like:

├── node_modules
│   ├── jquery
│   │   └── dist
│   │       └── jquery.min.js
│   └── katex
│       └── dist
│           ├── fonts
│           │   ├── KaTeX_Size1-Regular.eot
│           │   ├── KaTeX_Size1-Regular.ttf
│           │   ├── KaTeX_Size1-Regular.woff
│           │   └── KaTeX_Size1-Regular.woff2
│           ├── katex.min.css
│           └── katex.min.js
├── src
│   ├── assets
│   │   ├── tiny.svg
│   │   └── welcome.svg
│   └── html
│       └── index.html
└── vendor
    └── blerb.js

And a webtamp config like:

const camelcase = require('camelcase');
const webtamp = require('webtamp');

module.exports = {

  output: {
    dir: 'dist',
    name: '[hash:8]-[name].[ext]',

  assets: {
    html: { type: 'local', src: 'src/html', files: '**/*.html', outputName: '[path]/[basename]' },
    images: { type: 'local', src: 'src/assets', files: '**/*.{svg,ico}', manifest: camelcase },
    main: [ 'blerb', 'katex' ],

  optional: {

    jquery: {
      type: 'cdn',
      url: ``,
      integrity: { files: 'node_modules/jquery/dist/jquery.min.js' },

    blerb: [
      { type: 'local', files: 'vendor/blerb.js', manifest: true },
      'jquery', // This here means blerb requires jquery

    katex: [
      { type: 'local', src: 'node_modules/katex/dist', files: '*.min.js' },
      { type: 'local', src: 'node_modules/katex/dist', files: 'fonts/**/*', transitive: true },

  plugins: [ => /\.svg$/.test(i.dest) && i.size() < 4096),

Now lets say the content of your src/html/index.html is as follows:

    <!-- *********** ↓ replaces this ↓ *********** -->
    <require asset="main" />
    <!-- *********** ↓ replaces these ↓ *********** -->
    <img src="webtamp://manifest/tinySvg" alt="Tiny!">
    <img src="webtamp://manifest/welcomeSvg" alt="Welcome!">

After running webtamp, you'll have a dist directory like this:

├── 03bef6aa-katex.min.js
├── 1b40ddd6-katex.min.css
├── 5eb3a560-welcome.svg
├── 88fee037-blerb.js
├── fonts
│   ├── KaTeX_Size1-Regular.eot
│   ├── KaTeX_Size1-Regular.ttf
│   ├── KaTeX_Size1-Regular.woff
│   └── KaTeX_Size1-Regular.woff2
└── index.html

And the dist/index.html after the Html.replace plugin now looks like this:

    <!-- *********** ↓ replaces this ↓ *********** -->
    <script src="" integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44=" crossorigin="anonymous"></script>
    <script src="/88fee037-blerb.js"></script>
    <script src="/03bef6aa-katex.min.js"></script>
    <link  href="/1b40ddd6-katex.min.css" rel="stylesheet">
    <!-- *********** ↓ replaces these ↓ *********** -->
    <img src="data:image/svg+xml;base64,VGhpcyBpcyBqdXN0IGFuIGV4YW1wbGUK" alt="Tiny!">
    <img src="/5eb3a560-welcome.svg" alt="Welcome!">


If you like what I do —my OSS libraries, my contributions to other OSS libs, my programming blog— and you'd like to support me, more content, more lib maintenance, please become a patron! I do all my OSS work unpaid so showing your support will make a big difference.


Copyright 2017 David Barri

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.