Rob Palmer

@robpalmer.bsky.social

8185 Followers 789 Following

JavaScript Infrastructure & Tooling at Bloomberg. Co-chairing TC39. Likely to tweet tech stuff about JS & software performance. Opinions are my own.

const { shape, color, mass, } = await Promise.allKeyed({ shape: getShape(), color: getColor(), mass: getMass(), });
Five engineers in a glass meeting room with a whiteboard wall
nub. $ nub index.ts # TypeScript-first Node.js runtime $ nub run dev # 24x faster pnpm run $ nubx prisma generate # 19× faster npx $ nub install # 3x faster pnpm install $ nub watch sic/server.ts 非 native watch mode $ nub pm shim # built-in Corepack-style shims $ nub node install 26 # Node version manager
The API A thread is a function call on another core: const t = new Thread((a, b) => { return expensive(a, b); }, x, y); t.join(); // blocks, returns fn's value or rethrows its exception await t.asyncJoin(); // same, as a promise; never blocks Thread.current; // your Thread t.id; // engine thread id, main is 0
const x01 = 1 as number * 2; const x02 = 1 as any as number * 2; const x03 = 1 + 1 as number * 2; // Error const x04 = 1 + 1 as any as number * 2; // Error const x05 = 1 as number + 1 * 2; const x06 = 1 as any as number + 1 * 2;
as/satisfies precedence and erasableSyntaxOnly Issue: #63527 - Problem: 1 + 2 as number / 3 parses as ((1 + 2) as number) / 3 - This can't be emitted without parenthesizing 1 + 2, since 1 + 2 / 3 has different meaning
Bloomberg grew while others cut – and that’s the retention strategy. Doubling from 5,000 to 10,000 engineers while competitors downsized sends a clear signal: we won’t discard you when markets turn.
35-ish delegates in JetBrains office. Dmitry is in the middle on the floor.
Me: Yes the one in putty tightened fast at the end. I used 40mm m5s. Seemed very solid and it supports the pole and the curtains fine. It may not be the best hung curtain pole in the world, but it's up there. Gemini: That rapid tightening at the end is the exact mechanical feedback you want. It confirms the 40mm M5 screw fully expanded the plug against the unyielding epoxy, creating a high-torque friction lock rather than just compressing soft material. ​"Up there" is the primary requirement for a curtain pole. The structural foundation you built with the epoxy cast ensures it will stay there under the dynamic load of the curtains.
Johnny English film poster
Source Maps: Shipping Features Through Standards Published on 10 March 2026 Source maps are a vital part of modern web development.
const odds = [1, 3, 5].values(); const evens = [2, 4, 6].values(); for (const n of Iterator.concat(odds, evens)) { console.log(n); // 1, 3, 5, 2, 4, 6 }
GitHub PRs for SWC
A JS Marty McFly and "Temporal API" that looks like the logo from Back to the Future
Delegates of TC39 in Google's Chelsea Market office
A chocolate cake with white writing that says "Temporal is Stage 4" but might say "Tom Poral is Stage 4"
new Error(message, { limit: 3 }) new TypeError(message, { limit: 0 }) new RangeError(message, { limit: 50 }) new AggregateError(iterable, message, { limit: Infinity }) // ... applies to all built-in Error constructors that accept an options bag
let fs; try { fs = import.sync('node:fs'); } catch {} if (fs) { // Use node:fs, only if it is available }
// Currently let prefs = new getUserPrefs(); if (!prefs.has("useDarkmode")) { prefs.set("useDarkmode", true); // default to true } // Using getOrInsert let prefs = new getUserPrefs(); prefs.getOrInsert("useDarkmode", true); // default to true
Jon and his chunky dog.
Sure, the best time to replace Date would’ve been back in 1995, but hey: the second best time is Temporal.Now, right?
From the article "Temporal has still not made it to many JavaScript engines. At the time of writing, it is available in Firefox and nowhere else" Plus red annotation "Not true: now in Chrome!"
A graph from the 2025 Octoverse report that shows the combined JS/TS usage being nearly double the next most used language.
Our plans are measured in centuries
~35 TC39 delegates on the stage in front of a sign that says "Bloomberg Welcomes Ecma TC39"
const a = [1, 2, 3]; a.description = "coords"; Object.defineProperty(a, "secret", { value: true, enumerable: false, }); a[5] = 42; Object.getNonIndexStringProperties(a); // ["description"] ("secret" is non‑enumerable) Object.getNonIndexStringProperties({ foo: 1, bar: 2 }); // ["foo", "bar"] (works on any object)
Single Unit Identifier watt: SI derived unit for power (appliance ratings, device specifications) kilowatt: Common power ratings (EV charging rate, solar, HVAC systems) kilowatt-hour: Primary unit for electrical energy consumption (utility bills, EV charging, home energy)
const obj = { a: 1, b: 2 }; const count = Object.keys(obj).length;
const enc = new TextEncoder(); const u8_1 = enc.encode('hello world'); const u8_2 = enc.encode('world'); u8_1.find(u8_2); // 6 … returns index of found seq. u8_1.contains(u8_2); // true … returns true/false
const enc = new TextEncoder(); const u8_1 = enc.encode('hello'); const u8_2 = enc.encode('world'); const u8_3 = Uint8Array.concat([u8_1, u8_2]);
let formatter = new Intl.NumberFormat(locale, { style: "unit", }); let result = formatter.format({ number, unit, });
const { shape, color, mass, } = await Promise.allKeyed({ shape: getShape(), color: getColor(), mass: getMass(), });
Iterator.zip([ [0, 1, 2], [3, 4, 5], ]).toArray() /* Produces: [ [0, 3], [1, 4], [2, 5], ] */
let lows = Iterator.from([0, 1, 2, 3]); let highs = Iterator.from([6, 7, 8, 9]); let lowsAndHighs = function* () { yield* lows; yield* highs; }(); Array.from(lowsAndHighs); // [0, 1, 2, 3, 6, 7, 8, 9]
Week Data let he = new Intl.Locale("he") he.getWeekInfo() // {firstDay: 7, weekend: [5, 6]} let af = new Intl.Locale("af") af.getWeekInfo() // {firstDay: 7, weekend: [6, 7]} enGB = new Intl.Locale("en-GB") enGB.getWeekInfo() // {firstDay: 1, weekend: [6, 7]} let msBN = new Intl.Locale("ms-BN") msBN.getWeekInfo() // {firstDay: 7, weekend: [5, 7]} // Brunei weekend is Friday and Sunday
Bloomberg meeting room in Tokyo. 40 seats in a square configuration.
19h 50m of scheduled discussions annotated with a shocked face Agenda for the 111th meeting of Ecma TC39 Host: Bloomberg Dates and times: 10:00 to 17:00 JST (Asia/Tokyo) on Tuesday 18 November 2025 10:00 to 17:00 JST (Asia/Tokyo) on Wednesday 19 November 2025 10:00 to 16:00 JST (Asia/Tokyo) on Thursday 20 November 2025 Location: Tokyo, Japan
Online learning platform for Computer Science prompts you to pay for a premium service to explain Variables and Constants in more detail.
Graph showing JS+TS contributor count over the last 3.5 years. JS/TS is almost double the nearest data series (Python) over that period, and shows steeper acceleration towards the end.
// Currently let prefs = getUserPrefsMap(); if (!prefs.has("useDarkmode")) { prefs.set("useDarkmode", true); // default to true } // Using getOrInsert let prefs = getUserPrefsMap(); prefs.getOrInsert("useDarkmode", true); // default to true
It’s important to emphasize that Vite+ is a separate, additive layer built on top of the open source projects we maintain. All existing projects — Vite, Vitest, Rolldown, and Oxc — will remain open source under MIT forever. Since Vite+ relies on these open source projects, improving Vite+ requires improving them as well. You are welcome to hold us accountable to that commitment.
A slide titled: Vite+ And many CLI commands: vite dev vite build vite lint vite fmt vite test vite lib vite new vite run vite install vite ui
Evan You on stage at ViteConf announcing Vite+
Simpsons scene where Moe says "that's the worst name I ever heard" before joey jojo gets upset and leaves.
OverlookMotel at a podium in front of an Oxlint "Get Involved" slide
Bloomberg folk in front of the Royal Observatory, Greenwich on a day with fine weather. The group are potentially straddling the invisible Prime Meridian line that runs through it.
Make the case I didn't have a case study that I could point to in my meetings with my manager. All I had was the reasonable premise that doing one less thing (transpilation) and using a more efficient module system (ESM) would make things faster. Thanks to this blog post, you do not have this challenge. You can tell your manager, "A charismatic engineer on the internet said we can expect a 30-40% decrease in local development tasks, as well as at least a few minutes in our CI pipelines. Migrating to Node type stripping will help us ship features, address bugs faster, and improve many developer productivity metrics that influence overall software engineer happiness. We can put guardrails in place to prevent the risk of excessive engineer happiness. I hereby pledge to throw sand in the eyes of any engineer guilty of gratuitous happiness."
2025-07-31, Version 22.18.0 'Jod' (LTS), @aduh95 Notable Changes Type stripping is enabled by default Node.js will be able to execute TypeScript files without additional configuration: $ echo 'const foo: string = "World"; console.log(`Hello ${foo}!`);' > file.ts $ node file.ts Hello World!
let lows = Iterator.from([0, 1, 2, 3]); let highs = Iterator.from([6, 7, 8, 9]); let lowsAndHighs = function* () { yield* lows; yield* highs; }(); Array.from(lowsAndHighs); // [0, 1, 2, 3, 6, 7, 8, 9]