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firebase / firebase-tools

The Firebase Command Line Tools
MIT License
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'firebase serve' does not work with javascript import with module resolution #818

Closed JeanRemiDelteil closed 6 years ago

JeanRemiDelteil commented 6 years ago

Version info

v3.19.3

Platform Information

All

Steps to reproduce

On a project that use the latest Javascript imports and NPM package (for example: Polymer) try running the firebase server.

For example the https://github.com/Polymer/pwa-starter-kit can be deployed via firebase deploy but can not be tested with firebase serve.

This defeats the purpose of a one command server which we all love.

Expected behavior

The app can be served with firebase serve

Actual behavior

The app can only be served with polymer serve

WHY ?

Issues lies in the javascript import Node module resolution:

import { LitElement, html } from '@polymer/lit-element';

while front javascript imports like:

import { LitElement, html } from '/node_modules/@polymer/lit-element.js';

This way of writing import is not in the ECMA specs for browser Javascript, however the polymer team and a lot of front-end libraries are now using NPM to publish front-end packages.

To support using NPM packages in the development of Firebase hosted site, the CLI should modify the import on-the-fly, like polymer serve already does.

I have to stress that the issue only lies when developing and testing the site, not when deploying. This is because a build step correctly re-write those imports / bundles them.

mbleigh commented 6 years ago

Thanks for the feature request, but Firebase Hosting tries to remain agnostic to the actual tooling you're using to build your front end. Introducing this behavior would mean that we are adding additional code dependencies and runtime CPU usage to firebase-tools for a practice that is by no means universal at this time.

What we would like to do is provide better ways to run firebase serve along-side your existing toolchain. Nothing specific to talk about here yet, but it's something we're looking into.

JeanRemiDelteil commented 6 years ago

It would be awesome if we could run firebase serve while providing a custom file provider, as superstatic does ! My try at solving this issue resulted in a combined server, first from poly-serve to prepare the files, then with superstatic to easily apply the existing server logic. It's far from ideal, but working.