Registry / web-framework / es-dev-server

es-dev-server

library2.1.0jsnpmunverified

ES Dev Server (version 2.1.0, though the project itself has seen its main development move to a new name) is a development server designed for modern web applications that leverage native ES modules directly in the browser, thereby eliminating the need for a separate bundling step during development. It offers features like efficient browser caching for fast reloads, on-demand code transformation for older browser compatibility, resolution of bare module imports (`--node-resolve`), and automatic browser reloading on file changes (`--watch`). Its key differentiator lies in promoting a "no-build" development workflow. While it remains functional and receives bug fixes, new development and active feature work have moved to its successor, `@web/dev-server`. Users are generally advised to use `@web/dev-server` for new projects and consider migrating existing ones.

web-framework http-networking

npm install es-dev-server

github ↗package ↗

INSTALL

IMPORT

SIG · ES-DEV-SERVER

es-dev-server

web-frameworkjavascriptv2.1.0

Install

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Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

es-dev-server CLI

✓ npx es-dev-server [options]

✗ es-dev-server [options]

Primary interaction is via CLI. Using `npx` ensures the locally installed version is used.

createConfig

✓ import { createConfig } from 'es-dev-server'

✗ const { createConfig } = require('es-dev-server')

For programmatic configuration in ESM environments. CommonJS `require` might lead to issues in mixed module environments.

startServer

✓ import { startServer } from 'es-dev-server'

✗ const { startServer } = require('es-dev-server')

For starting the server programmatically in ESM environments.

Demonstrates setting up `es-dev-server` to serve a simple HTML file with native ES module imports, using `npm scripts` for easy execution and `--node-resolve` for bare module support.

{ "name": "my-es-dev-app", "version": "1.0.0", "description": "A simple app served by es-dev-server", "scripts": { "start": "es-dev-server --app-index public/index.html --node-resolve --watch --open --root-dir public" }, "devDependencies": { "es-dev-server": "^2.1.0", "lit": "^2.0.0" } }  <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>ES Dev Server App</title> </head> <body> <h1>Welcome to ES Dev Server!</h1> <script type="module"> // This bare module import requires --node-resolve import { html } from 'lit'; console.log('App loaded via native ES Modules.'); document.body.innerHTML += html`<p>Lit-html import worked!</p>`; </script> </body> </html> # To run: # npm install --save-dev es-dev-server lit # npm run start

es-dev-server --version

Debug

Known issues

breakingThe `es-dev-server` project has been renamed to `@web/dev-server` (part of Open Web Components project). New development and active feature work is focused on the new package. Users are strongly recommended to migrate to `@web/dev-server` for new projects and consider upgrading existing ones.

fix

Migrate your project from `es-dev-server` to `@web/dev-server` following the official migration guides provided by the Open Web Components project. Ensure you update your `package.json` dependencies and server configuration.

affects: *

gotcha`es-dev-server` requires Node.js v10 or higher to function correctly. Older Node.js versions may lead to unexpected errors or a failure to start the server.

fix

Ensure your Node.js installation is version 10 or greater. Use a Node Version Manager (like `nvm`) to easily switch or update your Node.js environment.

affects: *

gotchaWhen serving over HTTP2 (using the `--http2` flag), `es-dev-server` uses self-signed SSL certificates by default. This will cause browser security warnings (e.g., 'Your connection is not private').

fix

Accept the self-signed certificate in your browser for local development. For more permanent solutions or different environments, you may need to configure `es-dev-server` to use trusted SSL certificates.

affects: *

gotchaMisconfiguration of `--node-resolve` and `--compatibility` flags can lead to issues. For instance, `--node-resolve` is crucial for handling bare module imports (e.g., `import 'lit'`), while `--compatibility` transforms code for older browsers, which might conflict or be unnecessary if not carefully managed.

fix

Carefully review the documentation for `node-resolve` and `compatibility` options. Enable `--node-resolve` if you are using bare module specifiers. Adjust `--compatibility` based on your target browser support matrix to avoid over-transpiling or missing necessary polyfills.

affects: *

Errors

Common errors & fixes

Error: Cannot find module 'es-dev-server'

The `es-dev-server` package is not installed or the `es-dev-server` command is not accessible in your system's PATH.

fix

Run `npm install --save-dev es-dev-server` to install the package. If running via CLI, ensure you use `npx es-dev-server` or define it as a script in `package.json` (e.g., `"start": "es-dev-server ..."`).

Address already in use :::XXXX (where XXXX is a port number)

Another process on your machine is currently using the specified or default HTTP port (e.g., 8000).

fix

Change the port `es-dev-server` listens on using the `--port` flag (e.g., `es-dev-server --port 8001`) or by modifying your configuration file. Alternatively, identify and terminate the process currently occupying the port.

ReferenceError: require is not defined in ES module scope

You are attempting to use CommonJS `require()` syntax within a JavaScript file that is being interpreted as an ES module (e.g., a programmatic config file or a custom plugin script).

fix

Rewrite the problematic file to use ES module `import` syntax instead of `require()`. Ensure your `package.json` `type` field is correctly set, or use appropriate file extensions (e.g., `.cjs` for CommonJS, `.mjs` for ESM).

Upgrade

Version history

2.1.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

5 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/open-wc/es-dev-server ↗

packagehttps://www.npmjs.com/package/es-dev-server ↗