ESM

A fast, global content delivery network for ES Modules. All modules are transformed to ESM by esbuild in NPM.

Import from URL

import React from 'https://esm.sh/react'

Specify version

import React from 'https://esm.sh/[email protected]'

Submodule

import { renderToString } from 'https://esm.sh/react-dom/server'

or import non-module(js) files:

import 'https://esm.sh/tailwindcss/dist/tailwind.min.css'

Specify ESM target

import React from 'https://esm.sh/react?target=es2020'

Avaiable

target

Development mode

import React from 'https://esm.sh/react?dev'

Bundle mode

import React from 'https://esm.sh/[react,react-dom,swr]/react'
import ReactDom from 'https://esm.sh/[react,react-dom,swr]/react-dom'

or your can define the bundle list in

import-map.json

{
    "imports": {
        "https://esm.sh/": "https://esm.sh/[react,react-dom,swr]/",
        ...
    }
}

import React from 'https://esm.sh/react' // actual from 'https://esm.sh/[react,react-dom,swr]/react'

⚠️ The bundling packages in URL are litmited up to 10, to bundle more packages, please use the esm client(WIP).

Deno compatibility

esm.sh provides polyfills for the node internal modules(fs, os, etc) with

deno.land/std/node

postcss

import postcss from 'https://esm.sh/postcss'
import autoprefixer from 'https://esm.sh/autoprefixer'

const css = (await postcss([ autoprefixer]).process(    backdrop-filter: blur(5px);     user-select: none;).async()).content

X-Typescript-Types

By default, esm.sh will response a custom HTTP header of

X-TypeScript-Types

You can pass the

no-check

types

import unescape from 'https://esm.sh/lodash/unescape?no-check'

Caveats

Different with Skypack and jspm, esm.sh will bundle all dependencies(exclude peerDependencies) for each package, that means there may be redundant contents transmitted when you are importing multiple packages.
This should be improved when the http/3(quic) is ready. For now the best practice is using the bundle mode.

As optional, you can split code manually with

external

import React from 'https://esm.sh/[email protected]'
import useSWR from 'https://esm.sh/[email protected]'

Network of esm.sh

• Main server in HK
• Global CDN by Cloudflare
• China CDN by Aliyun

Self-Hosting

You will need Go 1.14+ to compile the server, and ensure supervisor installed on your host machine.
The server runtime will install the latest nodejs (14+ LTS) automatically.

$ git clone https://github.com/postui/esm.sh
$ cd esm.sh
$ sh ./scripts/deploy.sh