Journal

Notes from things that broke.

Short write-ups on correctness, infrastructure and the specific bugs that changed how I build. RSS.

7 October 2026

JavaScript using: automatic resource cleanup with Symbol.dispose

JavaScript's using declaration runs cleanup automatically when a scope ends. How Symbol.dispose, await using and DisposableStack work, and where it runs.

6 min · JavaScript · Node.js · Web Platform

6 October 2026

Rate limiting algorithms: token bucket vs sliding window

How rate limiting algorithms work: fixed window, sliding window and token bucket, where each one leaks bursts, and which to pick for your API.

7 min · Scaling · Architecture · APIs

5 October 2026

Cloudflare Clef: decision models for AI agents on Workers AI

Cloudflare Clef is an open-weight decision model that returns calibrated probabilities instead of text. How it works and when to use it over an LLM.

6 min · AI · LLMs · Cloudflare · Agents

4 October 2026

Why JavaScript sort() puts 10 before 9, and how to fix it

JavaScript's array sort() orders numbers as strings, so 10 lands before 9. Here's why, the comparator fix, and the a > b trap that sorts nothing.

6 min · JavaScript · Arrays · Debugging

3 October 2026

HTML invoker commands: open dialogs without JavaScript

HTML invoker commands let a button open dialogs and toggle popovers with commandfor and command. How they work, custom commands, and the form gotcha.

5 min · HTML · Web Platform · Accessibility

2 October 2026

Cache stampede: how to prevent the thundering herd

A cache stampede hits your database when a hot key expires. How request coalescing, locks, early refresh and stale-while-revalidate stop it.

7 min · Caching · Scaling · Architecture

1 October 2026

GPT-6 prompt caching: breakpoints, pricing and cache misses

How GPT-6 prompt caching works: explicit breakpoints, the 30-minute TTL, 1.25x writes vs 0.1x reads, and how to change tools or effort without a cache miss.

6 min · AI · LLMs · OpenAI · Performance

29 September 2026

SQL NOT IN returns no rows when the subquery has a NULL

One NULL in the subquery and SQL NOT IN returns no rows at all. No error, no warning. Here is why, and why NOT EXISTS is the fix.

5 min · PostgreSQL · SQL · Debugging

28 September 2026

Why new Date('2026-09-30') shows the wrong day in JavaScript

A date-only string is parsed as UTC midnight, a date-time string as local time. Half the world sees yesterday, and India never notices.

4 min · JavaScript · Dates · Debugging

26 September 2026

The JavaScript Temporal API: what it is and how to use it now

The JavaScript Temporal API reached Stage 4 and ships in Chrome, Firefox and Node 26. Here are its types, the DST rules, and how to migrate from Date.

6 min · JavaScript · Dates · Web Platform

6 August 2026

Matter.js calls preventDefault on every touch, and traps your page

A physics toy on a phone stopped the page scrolling. Not when you touched an object — when you touched anywhere near it.

2 min · JavaScript · Mobile · Canvas

30 July 2026

A portalled <dialog> does not fire React's onClose

Closing the modal left the app permanently frozen. The event was firing. React just was not listening for it.

2 min · React · Accessibility · Debugging

23 July 2026

Multi-tenant isolation belongs in the data layer, not in every query

One endpoint missing a WHERE clause shows one customer another customer's drafts. You find out from the customer.

2 min · SaaS · PostgreSQL · Architecture

16 July 2026

Designing for the spike, not the average

A platform that is quiet for days and then serves an entire region inside two minutes. The load shape decided the architecture before any feature did.

2 min · Architecture · AWS · Scaling

9 July 2026

Cloudflare was revalidating every hashed asset on every page load

Workers Assets ships a default cache header that is correct for hand-written files and wrong for every file a bundler emits.

2 min · Cloudflare · Performance · Deployment

2 July 2026

setPointerCapture on pointerdown silently kills every click

A draggable marquee where none of the cards were clickable. The drag code was correct. It was one line, in the wrong handler.

2 min · JavaScript · UI · Debugging

25 June 2026

Never trust the delta your frame loop hands you

An unclamped frame delta made a WebGL hero teleport instead of resume, and pushed an interpolation past its target into negative values.

2 min · Animation · Performance · WebGL

18 June 2026

overflow-x: auto quietly makes a vertical scroll container too

Three full-bleed carousels on a phone ate every upward swipe. The cause was one line of CSS that does something the property name does not say.

2 min · CSS · Mobile · Debugging

← Back to Syed’s work

Notes from things that broke.Notes from things that broke.

JavaScript using: automatic resource cleanup with Symbol.dispose

Rate limiting algorithms: token bucket vs sliding window

Cloudflare Clef: decision models for AI agents on Workers AI

Why JavaScript sort() puts 10 before 9, and how to fix it

HTML invoker commands: open dialogs without JavaScript

Cache stampede: how to prevent the thundering herd

GPT-6 prompt caching: breakpoints, pricing and cache misses

SQL NOT IN returns no rows when the subquery has a NULL

Why new Date('2026-09-30') shows the wrong day in JavaScript

The JavaScript Temporal API: what it is and how to use it now

Matter.js calls preventDefault on every touch, and traps your page

A portalled <dialog> does not fire React's onClose

Multi-tenant isolation belongs in the data layer, not in every query

Designing for the spike, not the average

Cloudflare was revalidating every hashed asset on every page load

setPointerCapture on pointerdown silently kills every click

Never trust the delta your frame loop hands you

overflow-x: auto quietly makes a vertical scroll container too

Notes from things that broke.Notes from things that broke.

JavaScript using: automatic resource cleanup with Symbol.dispose

Rate limiting algorithms: token bucket vs sliding window

Cloudflare Clef: decision models for AI agents on Workers AI

Why JavaScript sort() puts 10 before 9, and how to fix it

HTML invoker commands: open dialogs without JavaScript

Cache stampede: how to prevent the thundering herd

GPT-6 prompt caching: breakpoints, pricing and cache misses

SQL NOT IN returns no rows when the subquery has a NULL

Why new Date('2026-09-30') shows the wrong day in JavaScript

The JavaScript Temporal API: what it is and how to use it now

Matter.js calls preventDefault on every touch, and traps your page

A portalled <dialog> does not fire React's onClose

Multi-tenant isolation belongs in the data layer, not in every query

Designing for the spike, not the average

Cloudflare was revalidating every hashed asset on every page load

setPointerCapture on pointerdown silently kills every click

Never trust the delta your frame loop hands you

overflow-x: auto quietly makes a vertical scroll container too

Notes from things that broke.

Notes from things that broke.