Express middleware to transform bare module specifiers on-the-fly.
npm install express-transform-bare-module-specifiers> Express middleware to transform bare module specifiers on-the-fly.
1. Install the middleware:
``bash`
npm i express-transform-bare-module-specifiers
2. Import (or ) this package:
`js
// ES Modules
import transformMiddleware from 'express-transform-bare-module-specifiers';
// CommonJS
const transformMiddleware = require('express-transform-bare-module-specifiers').default;
`
3. Configure and apply the middleware:
`js`
// Using defaults:
app.use('*', transformMiddleware());
// Using a custom rootDir and modulesUrl:
app.use('*', transformMiddleware({
rootDir: path.resolve(__dirname, '/bundles/my-bundle'),
modulesUrl: '/bundles/my-bundle/node_modules'
}))
- : the project base directory. This should contain the package.json and node_modules of the application. It defaults to process.cwd().modulesUrl
- : is the route that you will be serving your node_modules directory from. It defaults to /node_modules.
ES Modules are great. However, it can be difficult to incorporate existing npm packages, because you have to specify the fully-qualified path to the entrypoint of each and every npm package you wish to use. That is to say: you can't do this:
`js`
import * as noop from 'noop3';
... you instead must do this (for example):
`js`
import * as noop from '../node_modules/noop3/index.js';
You can see how this would rapidly become very hard to maintain.
This limitation is present because the ES Modules spec currently does not support so-called "bare module specifiers". That is: any module specifier which does not start with a relative or absolute path, such as /, ./, ../, etc.
This middleware uses a single babel transform to convert these "bare module specifiers" in your code to fully-qualified relative paths. This means that you can just write code which references npm packages installed in your node_modules, and this middleware will handle translating those package names to fully-qualified paths on-the-fly.
This middleware is based entirely on the implementation found in polyserve. Except, it uses the babel-plugin-bare-import-rewrite` babel plugin instead of the one built into polymer-build.