A micromodule hosting and registry for JavaScript

Usage no npm install needed!

<script type="module">
  import exprs from 'https://cdn.skypack.dev/exprs';



The command-line interface for exprs.sh.

exprs is a micromodule hosting and registry service for JavaScript. No worry about setting lint, formatting, transpilations or test runners. Just write and share your code.


  • Just expression. A micromodule is a single expression of JavaScript, which will do one thing well.
  • Immutable. All micromodules are immutable and would never dissapear.
  • Deterministic. With aliasing, your dependencies are not unintentionally upgraded and are always the exact same.
  • Transpile on install. The transpilation runs on the installtion phase, so module users can select supporting environments instead of authors.
  • No task setup. Common tasks like linting and formatting are integrated into the platform.
  • No name collision. All micromodules have an unique name and can have alias names under your namespace.

Get started

Install the package from npm:

npm install --global exprs

# or with `yarn`
yarn global add exprs

Install a micromodule:

exprs add @nkzawa/leftPad

Use it on your applications as always you do with node modules:

const leftPage = require("@nkzawa/leftPad");


exprs install

Install micromodules defined in package.json. This command is the default so you can execute it as just exprs.

exprs install

# or just

dependencies and devDependencies are defined on the exprs field:

  "exprs": {
    "dependencies": {
      "@nkzawa/leftPad": "leftPad_a01",
      "@username/aliasName": "moduleName_b12",
      "someModule_c23": "someModule_c23"

To not install devDependencies, use the --production option:

exprs --production

exprs add <module|alias...>

Install a micromodule from the registry and add it to package.json.

exprs add @nkzawa/leftPad

To install as devDependencies, run with the --dev (or -d) option:

exprs add --dev @nkzawa/leftPad

exprs upgrade [alias...]

Upgrade aliases to the latest version of micromodules.

exprs upgrade

exprs remove <module|alias...>

Uninstall a micromodule and remove it from package.json.

exprs remove @nkzawa/leftPad

exprs help

Display the help message.

exprs help

Integration with npm

When your npm package has dependencies on exprs micromodules, you want to setup a npm hook script to install micromodules along with npm install:

  "scripts": {
    "install": "exprs"
  "dependencies": {
    "exprs": "*"