esmoduleserve

This is a shim HTTP server for directly running ES6 modules with
non-precise import targets in your browser (without a bundling step).

It acts as a regular file server for a given directory, but exposes an
extra top-level path, /_m/, to serve rewritten modules relative to
that directory. Any file requested through this path will have its
imports (and re-exports) rewritten to point at precise resolved
scripts paths, referenced through /_m/.

Resolution is done via the node
algorithm, but letting
"module" or "jsnext" fields in package.json take precedence over
"main".

If some of the dependencies you load through this don't provide ES
module files, you are likely to find an error about a missing import
on your devtools console.

You can specify module files from parent directories of the served
directory using /__ to stand in for /.. in a /_m/ path. By
default, to avoid accidentally serving things you don't want to
expose, this is only allowed one parent directory deep.

Usage

You run the server for a given directory...

esmoduleserve demo/ --port 8080

It will start up an HTTP server on the given port, serving the content
of the demo directory statically. If there's a module called
demo.js in this directory, you can load it in an HTML file with a
script tag like this:

The options recognized by the command-line server are:

* --port to specify a TCP port to listen on. Defaults to 8080.

* --host to specify a hostname to listen on. Defaults to
"localhost".

* --depth to specify how many parent directories should be
accessible. Defaults to 1.

* --prefix to specify an alternative URL prefix for module
script URLs. Defaults to "_m".

The moduleserver.js file exports this functionality as HTTP
middleware. Usage looks something like:

const {ModuleServer} = require("esmoduleserve/moduleserver")
const moduleServer = new ModuleServer({root: "/some/path",
maxDepth: 2,
prefix: "_m"})

// In a server function
if (moduleServer.handleRequest(req, resp)) return

The handleRequest method handles only requests whose path starts
with the prefix. It returns true for such requests.

Source

This code is open-source under an MIT license. If you want to
contribute, create pull requests
on GitHub.