ESM

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

Import from URL

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

Specify version

import React from 'https://esm.sh/react@17.0.2'

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'

By default, esm.sh will check the User Agent of browser to get the build target, or set it by the target query. Avaiable target: es2015-es2020, esnext, and deno.

Bundle mode

import React from 'https://esm.sh/antd?bundle'

In bundle mode, all dependencies will be bundled into the package js file.

Development mode

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

Specify external deps

import React from 'https://esm.sh/react@16.14.0'
import useSWR from 'https://esm.sh/swr?deps=react@16.14.0'

Package CSS

import Daygrid from 'https://esm.sh/@fullcalendar/daygrid'

<link rel="styelsheet" href="https://esm.sh/@fullcalendar/daygrid?css">

Deno compatibility

esm.sh will resolve the node internal modules (fs, os, etc) with deno.land/std/node to support some packages working in Deno, like 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() 
console.log(css)

X-Typescript-Types

By default, esm.sh will response a custom HTTP header that is X-TypeScript-Types when the types(dts) is defined, this is useful for deno types check (link).

figure #1

You can pass the no-check query to disable the X-TypeScript-Types header if some types are incorrect:

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

Network of esm.sh

Main server in HK
Global CDN by Cloudflare
China CDN by Aliyun (use mmdb_china_ip_list to split traffic)

Self-Hosting

You will need Go 1.16+ to compile the server, and ensure supervisor installed on your host machine.
The server runtime will install the nodejs (14 LTS) automatically.

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