Tom Byrer tomByrer

ESM modules in node: npm edition

The proposal you’re about to read is not just a proposal. We have a working implementation of almost everything we discussed here. We encourage you to checkout and build our branch: our fork, with the relevant branch selected. Building and using the implementation will give you a better understanding of what using it as a developer is like.

Our implementation ended up differing from the proposal on some minor points. As our last action item before making a PR, we’re writing documentation on what we did. While I loathe pointing to tests in lieu of documentation, they will be helpful until we complete writing docs: the unit tests.

This repo also contains a bundled version of npm that has a new command, asset. You can read the documentation for and goals of that comma

Note: I'm not involved in Prepack in any way — please correct me if I say anything incorrect below!

A few people have asked me if Prepack and Svelte are similar projects with similar goals. The answer is 'no, they're not', but let's take a moment to explore why.

What is Prepack?

Prepack describes itself as a 'partial evaluator for JavaScript'. What that means is that it will run your code in a specialised interpreter that, rather than having some effect on the world (like printing a message to the console), will track the effects that would have happened and express them more directly.

So for example if you give it this code...

Go to the remote repo and delete outdated branches
Then either:
- Locally cleanup only merged branches: git branch --merged | grep -v "\*" | xargs -n 1 git branch -d

Locally remove fetched, outdated branches: git for-each-ref --format='%(refname:short) %(upstream)' refs/heads/ | awk '$2 !~/^refs\/remotes/' | xargs git branch -D”

How to append line numbers in front of each line in a file?

Just use cat. No kidding, cat has the -n option to number the output lines, starting at 1:

cat -n file.txt

This works well both on Linux and Mac. Use the shell redirection to keep the output in a new file (don’t override the original file with the redirection though).

In an effort to improve the quality of search results on sites like https://npmjs.com, there has been more and more discussion about factoring in the ranking/scoring of dependencies to influence search results. The general idea is that a library should be ranked not only on its own merits, but dependencies should weigh into the score as well.

I’m not sure what my opinion is on this yet. I was initially in favor of this, and still might be, but this document is a summary of some things that crossed my mind about the topic.

Should dependencies weigh into the search score for a library?

Some very popular libraries on npm are very poorly written, but solve problems that are sufficiently complex that few alternatives exist. From a scoring standpoint, this alone wouldn't matter because the law of averages would even it out. However...
It's possible for developers to write high quality, stable code on top of lesser quality libraries.
The better quality the code, and more knowledgable the maintainer

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	const fs = require('fs');
	const webpack = require('webpack');
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	const config = require('./webpack.config');
	const webpackMiddleware = require('webpack-dev-middleware');
	const webpackHotMiddleware = require('webpack-hot-middleware');

	const compiler = webpack(config);
	const middleware = (next) => {
	const mw = webpackMiddleware(compiler, {

	// basic destructuring
	const { key1 } = { key1: 10 } // key1 = 10
	const [x, y, z] = [1, 2, 3] // x = 1, y = 2, z = 3
	const [head, ...tail] = [1, 2, 3] // head = 1, tail = [2, 3]
	const { a: { b } } = { a: { b: 20 } } // b = 20

	// storing value in a variable with a different name
	const { key1: varForKey1 } = { key1: 20 } // varForKey1 = 20
	const { 'quoted-key': x } = { 'quoted-key': 10 } // x = 10

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