Fynn Ellie Be mvsde

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Learnings from `ts-blank-space`

tags: TypeScript, type erasure, type stripping

`ts-blank-space`

As part of my work on the JavaScript Tooling team at Bloomberg I have implemented an experimental (not yet used in production) package to transform TypeScript into JavaScript using a somewhat novel approach.

This is a description of what I learned from implementing the idea. The source code will be open sourced soon - it just needs some regular IP approval.

FAQ on the xz-utils backdoor (CVE-2024-3094)

This is a living document. Everything in this document is made in good faith of being accurate, but like I just said; we don't yet know everything about what's going on.

Update: I've disabled comments as of 2025-01-26 to avoid everyone having notifications for something a year on if someone wants to suggest a correction. Folks are free to email to suggest corrections still, of course.

Background

defaults:

npm config set init-author-name ""
npm config set init-author-url ""
npm config set init-author-email ""
npm config set init-license "ISC"
npm config set init-version "1.0.0"

custom (example)

npm config set init-author-name "Tierney Cyren"
npm config set init-author-url "https://bnb.im"

	// 3D Dom viewer, copy-paste this into your console to visualise the DOM as a stack of solid blocks.
	// You can also minify and save it as a bookmarklet (https://www.freecodecamp.org/news/what-are-bookmarklets/)
	(() => {
	const SHOW_SIDES = false; // color sides of DOM nodes?
	const COLOR_SURFACE = true; // color tops of DOM nodes?
	const COLOR_RANDOM = false; // randomise color?
	const COLOR_HUE = 190; // hue in HSL (https://hslpicker.com)
	const MAX_ROTATION = 180; // set to 360 to rotate all the way round
	const THICKNESS = 20; // thickness of layers
	const DISTANCE = 10000; // ¯\\_(ツ)_/¯

	/**
	* @param {import("@11ty/eleventy/src/UserConfig")} eleventyConfig
	*/
	module.exports = (eleventyConfig) => {
	return {};
	};

	{
	"explorer.experimental.fileNesting.enabled": true,
	"explorer.experimental.fileNesting.patterns": {
	"*.ts": "$(capture).js, $(capture).d.ts, $(capture).test.ts",
	"*.js": "$(capture).js.map, $(capture).min.js, $(capture).d.ts, $(capture).test.js",
	"*.jsx": "$(capture).js",
	".tsx": "$(capture).ts, $(capture)..ts, $(capture).*.tsx",
	"tsconfig.json": "tsconfig.*.json",
	"docker-compose.yml": "docker-compose.*.yml",
	".env": ".env.*",

	":" //#;exec /usr/bin/env node --input-type=module - $@<$0

	import process from 'process'

	const { argv } = process

	console.log(argv)

	let NETWORK_PRESETS = {
	'GPRS': {
	'offline': false,
	'downloadThroughput': 50 * 1024 / 8,
	'uploadThroughput': 20 * 1024 / 8,
	'latency': 500
	},
	'Regular2G': {
	'offline': false,
	'downloadThroughput': 250 * 1024 / 8,

	// This is Node script that uses Puppeteer (headless Chrome) to measure the decode time
	// of a single image injected into a blank HTML document. It uses minimist to take command
	// line arguments. Example usage: node measure-image-decode.js https://example.com/example-image.jpg
	// This example assumes you're running a local server to grab the blank document.
	// Thanks to Paul Irish and Tim Kadlec for their input!

	const puppeteer = require("puppeteer");
	const argv = require("minimist")(process.argv.slice(2));

	async function getDecode(url) {