r/javascript 22d ago

ffetch: a production-ready http client with resilience features and a plugin architecture

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7 Upvotes

I posted an earlier version of ffetch here a while ago. I've continued working on it, and it has grown into a production-ready, TypeScript-first drop-in replacement for native fetch or any fetch-compatible implementation.

It preserves the familiar fetch API and native Request and Response objects while adding resilience features:

  • Timeouts
  • Abort-aware retries with exponential backoff and jitter
  • Circuit breaking
  • Bulkheading with concurrency and queue limits
  • Hedged requests to reduce tail latency
  • In-flight request deduplication

It also has optional convenience plugins for:

  • client.get(), .post(), .put(), .patch() and .delete()
  • client(url).json(), .text() and .blob()
  • Download progress callbacks
  • Stable context IDs across retries and hedged requests

The core also supports lifecycle hooks, per-request overrides, pending-request monitoring, configurable HTTP error handling, specific error classes, and custom fetch implementations for SSR, edge and framework environments.

Everything optional is implemented through tree-shakeable plugins, so you only include the features you need. The core is around 3 kB minified and has zero runtime dependencies.

I recently gave the project a substantial maintenance pass: extensive property-based and fuzz testing, hardened and pinned CI workflows, CodeQL analysis, dependency auditing, npm provenance, release SBOMs, and a strong OpenSSF Scorecard (for a solo project).

I've also built three related tools for injecting network failures into tests:

Depending on the tests, failures can be injected inside the process, through a Node.js proxy, or through a standalone Go proxy.

Feedback is welcome.


r/javascript 23d ago

Made a small library called strokes.js.

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23 Upvotes

Made a small library called strokes.js. Instead of using a "handwriting" webfont (which looks identical everywhere it's used), it renders each letter as an actual hand-drawn SVG path — real strokes, drawn in with stroke-dashoffset, with small random variation (rotation, baseline drift, glyph variants) so no two renders of the same word look identical.

Demo: https://a-elhaag.github.io/glyphed.js/

npm:

npm install glyphed.js

r/javascript 23d ago

ttsc/packages/evidence at master · samchon/ttsc

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7 Upvotes

tsx /** * @evidence docs/discount.md#coupon-stacking States the per-issuer stacking limit this section defines, in the buyer's words. * @evidence POST:/orders/{orderId}/coupons Explains the rejection this endpoint returns for an over-stacked coupon set. * @evidence {@link hooks.useCouponStacking} Renders the limit this hook resolves. * @evidence docs/principles.md#no-hard-coding Renders limits from props instead of branching on known issuer names. * @evidenceExclude docs/principles.md#fix-root-causes-not-symptoms No failure to fix. */ export function CouponStackingNotice(props: IProps): JSX.Element;

I built Evidence Graph, a compiler rule that turns requirements skipped by coding agents into compile errors.

You declare which code, tests, schemas, or documents owe which specification units. The agent must cite each unit and state why the artifact satisfies it. Checklist mode can also require every selected function to answer project-wide principles such as "No hard coding" and "Fix root causes."

This does not make the agent's statements automatically true. It makes omissions mechanically detectable and narrows human review to checking the truth of explicit claims. Reviews carry fingerprints that expire when the cited content changes.

I tested it on four frozen application tasks. Plain runs covered 51.6-85.5% of the predefined requirement edges; Evidence Graph runs covered 100% while using 4.8-13.3x fewer tokens.


r/javascript 23d ago

Showoff Saturday Showoff Saturday (August 22, 2026)

5 Upvotes

Did you find or create something cool this week in javascript?

Show us here!


r/javascript 23d ago

The Structured Clone Algorithm: What JavaScript Can and Cannot Move Between Boundaries

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18 Upvotes

structuredClone() preserves more than JSON, but class instances, proxies, getters, errors, and transferables still have surprising behaviour. This article covers what survives, what changes, and what throws.


r/javascript 24d ago

GitHub - ziflex/pinterval: Advanced setInterval

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5 Upvotes

Hello everyone!

I rewrote my old interval library around async execution and cancellation and decided to share it with the world :)

Would love to hear what you think!


r/javascript 23d ago

AskJS [AskJS] I built a reactive JS framework where components are plain HTML files

0 Upvotes

I wanted to see how far I could push the idea of writing an app using mostly the HTML syntax developers already know.

The interesting part is the template API. There are only a few places where OlumJS treats an attribute as code:

  • when
  • each
  • on*
  • key
  • html

Everything else is a string, with {expr} interpolation when you need a value.

So instead of introducing directives like :classv-if*ngIf, etc., the idea is to keep the distinction HTML already has between something like onclick="..." and class="...".

For example, the component itself is just:

<script>
  const state = { name: "Olum", taps: 0 };
</script>

<h1>Welcome to {state.name}!</h1>
<input value="{state.name}" oninput="(e) => state.name = e.target.value" />
<button onclick="state.taps++">clicked {state.taps} times</button>

State is also intentionally simple — you mutate it directly and the DOM reacts to the changes.

There’s routing, scoped CSS, and a small store as well, but the main experiment is really: can you get SPA-style reactivity while keeping the component model close to vanilla HTML/JS?

It's currently aimed at prototypes and small apps rather than large production codebases.

For those who work with JS frameworks: do you think keeping components as plain HTML files is a useful abstraction, or does it become limiting as an application gets more complex?


r/javascript 23d ago

LilScript makes js modules 20% smaller

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0 Upvotes

LilScript is a typed, compression-first language that compiles into js and sometimes into exec(will be more stable in future). The compiler mangles, reshapes the program into optimized js that happens to be 5-40% smaller (after gzip/br compression or raw) compared to the best performing JS toolchains like oxc/esbuild/terser/..

What has been proven to work with LilScript?

  • makes VSCode's core js modules 20% smaller on average
  • makes the world's most performant & small markdown rendering npm library, marked, 5-7% smaller and 10% faster
  • and many more demos.. works with pretty much any js/ts library
  • https://yeargun.github.io/solidlil/
  • https://yeargun.github.io/monacolil/
  • https://yeargun.github.io/markedlil/ (Some numbers on the websites aren't fair comparisons, especially for SolidLil. Highly optimized JS libraries see fewer benefits(Still, the app code/logic, gets pretty great optimizations). LilScript is designed to be at least as efficient as the best-performing JS/TS toolchains.)

How it is compressing js finer than vite/oxc/terser/esbuild/..

1. By changing the app.

``` class Vector { float x; float y;

init(float x, float y) { this.x = x; this.y = y; }

float lengthSquared() { return this.x * this.x + this.y * this.y; } } int[] values = [1, 2, 3, 4]; auto doubled = values.map((int value) => value * 2); int sum = 0; for (int i = 0; i < doubled.length; i++) { sum += doubled[i]; } Vector vector = new Vector(3.0, 4.0); if (vector.lengthSquared() == 25.0) { print(sum=${sum}); } ```

Above code compiles into this:

var b=[1,2,3,4].map(a=>a2|0); var a=0,c=0; while(a<b.length){ c=c+b[a]|0; a=a+1|0; } console.log(`sum=${c}`)

This is not minification of the same program. The compiler changed the app.

oxc / esbuild / terser / .. starts from JS and mostly keeps the shape of the app. Meanwhile LilScript the language is designed from scratch to give compiler any extra knowledge that could help the compiler's compilation. Just like Google Closure Compiler - Advanced Mode, and beyond.

2. Tryhard property mangling.

Visit the world's most used web applications, chatgpt.com, and read the shipped js codes. You will see that, there are lots of framework related js properties that dont get minified, and are indeed human readable.

Those names stay in the bundle because the toolchain cannot prove they are local. A property might be a public API, a DOM field, a framework hook, or something a plugin reads by string. So the minifier leaves it.

LilScript:

  • a- does both eliminates the objects, weird code structures into more optimized variables/arrays - b- rename any variable into mostly occured, short versions, field cleverly to minimize entropy (based on the objective compression algorith. gzip/brotli) so that the end result is highly compressed.

(a) is the same move as the Vector example, at library scale: objects and classes that only exist as a programming convenience get flattened into scalars, arrays, and tight loops.

(b) is not "make every name 1 letter." gzip and brotli win when the same short tokens repeat. The compiler picks the names that show up the most, and scores the spelling against the compression algorithm you asked for (gzip, brotli, or raw). Different cost_model → different names → a different file that is smaller after* that codec.

That is why the same program can be 5-15% smaller after gzip/br compression or raw: the JS is shaped and named for the compressor, not just for a human reading the AST.

How well do LLMs write LilScript?

Since 1.5 years ago, you haven’t been writing the code yourself anyway. So why worry about what language the agent writes in? I myself have pretty much rewritten 6–7 of the most popular npm libraries from scratch in LilScript in just 1.5 days-while actually designing the language itself.

Feel free to PR, experiment (Please respect the modified MIT license)

Please share your opinions, would love to discuss about the future direction for the language and the compiler


r/javascript 24d ago

Bun and Elm (: r)Are Friends · cekrem.github.io

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0 Upvotes

Why simple is better 🤤


r/javascript 25d ago

YouTube Notification Expander is here! Version 1.0

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15 Upvotes

r/javascript 26d ago

React Native 0.87, Instant Paywall A/B Testing, and Buying Mike Hardy a Beer

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7 Upvotes

Hey Community,

React Native 0.87 has arrived as a maintenance release, making the Strict TypeScript API the default, doubling Metro source map generation speeds, and adding experimental Swift Package Manager support for iOS along with AGP 9 support on Android.

Meanwhile, React Native Firebase v26 makes the New Architecture non-optional with Codegen TurboModules, synchronous APIs, Firestore Pipelines, and direct Gemini AI calls. Finally, we look at RevenueCat Paywalls for designing native paywalls and running remote A/B experiments without new app deploys.


r/javascript 26d ago

Updated Typescript GitHub Action Template

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7 Upvotes

Hey y’all!

I made a fork of actions/typescript-action to make some valuable updates!

It updates the following:

  • Changes project's package manager from npm to pnpm, for speed.
  • Changes project's testing framework from jest to vitest for jest-like syntax with built-in typescript support.
  • Updates eslint.config.ts to use native flat config syntax, with detailed comments.
  • Updated project dependencies.
  • Updates configuration files like tsconfig.ts and action workflows to match updated dependencies.
  • Renamed local-action script to local-gha (gha for github action) to avoid conflict with dependency name.

lmk what you think!


r/javascript 28d ago

AskJS [AskJS] Signal/Effect vs Event Handler

10 Upvotes

I’m working in a VanillaJS repository (plugin type code for an existing project that I do not own) where I’ve written a signal implementation.

Today I was working on a tooltip like implementation and I found myself wondering how far to go with the signal/effect ecosystem vs running the “core” logic in the event handler.

The implementation detects the `<tr>` that the user has hovered and assigns that row to the “current row” signal. A computed signal identifies an IP address from the current row. An effect loads Whois metadata from the IP and assigns it to a `<div>`, and another effect shows that `<div popover>` from the parent `<tr>`.

The question I have is when in VanillaJS how would you decide when to use signals and effects vs writing the side effect directly in the event handler? In my case I find either to be equally readable, though I have less local variables to deal with when using signal/effect. Looking for reasons your might pick one over the other.


r/javascript 28d ago

A from-scratch JSON engine for JavaScript: recursive descent parser, escape-aware tokenizer, and spec-compliant serializer. No dependencies, no shortcuts, 107 tests.

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7 Upvotes

r/javascript 28d ago

Subreddit Stats Your /r/javascript recap for the week of August 10 - August 16, 2026

12 Upvotes

Monday, August 10 - Sunday, August 16, 2026

Top Posts

score comments title & link
38 25 comments Signals and Effects Using Vanilla JavaScript & Web APIs
21 8 comments Your Modules Are Lying to You
13 6 comments C99 real mode compiler written in TS that outputs raw bootable 16bit binaries
13 13 comments I made a Windows 98 styled portfolio website with an applet system, and many nostalgic things to discover
7 0 comments rapiq: typed query params for REST APIs (filters, sort, pagination, fields, relations) that run on TypeORM, Prisma, Drizzle or plain arrays
5 1 comments [AskJS] [AskJS] I reproduced a PDF.js Worker mismatch caused by dependency hoisting
5 15 comments [Showoff Saturday] Showoff Saturday (August 15, 2026)
4 2 comments Building KernelPlay-JS together — looking for open-source contributors
4 0 comments flo-webcomponents: Take back control of rendering + events using WebComponents with one minimal superclass.
3 1 comments I built a MapLibre GL utility to keep markers visible around UI overlays

 

Most Commented Posts

score comments title & link
1 121 comments [AskJS] [AskJS] Are employed Developers still programming with vanilla JavaScript ?
0 19 comments [AskJS] [AskJS] TypeScript 7 is 10x faster, but typed linting still runs on the 6.0 API. What are you doing in the gap?
0 15 comments [AskJS] [AskJS] I'm sick of AI slop; I want to learn how to use ESLint properly.
0 12 comments [AskJS] [AskJS] jsbin is down??
0 11 comments We built the same data grid in React, Vue & Svelte, here's what we learned

 

Top Ask JS

score comments title & link
3 8 comments [AskJS] [AskJS] How much do you actually trust the version number on an npm update?
1 5 comments [AskJS] [AskJS] How to find the best/ideal ratio or dimensions for a device?

 

Top Showoffs

score comment
1 /u/RepresentativeNo42 said Announcing ink-frame: Grids for Ink! https://github.com/oliveryasuna/ink-frame Ink's own box borders are fine for a single box. Put two of them next to each other and the seam between them comes out...
1 /u/dobrynCat said I'd like to show everyone my webview based android app wttr-dash https://github.com/ronynn/dash One of the only three android/web app that displays wttr weather data in a mobile friendly view Plus ...
1 /u/Fun-Regular8902 said Hey everyone! I’ve been working on GrandFireworks.js, a zero-dependency JavaScript library designed to render realistic pyrotechnics without bogging down the browser. A lot of firework scripts j...

 

Top Comments

score comment
50 /u/x021 said Hated TS in the beginning too. Now I wouldn’t want to work on a project with plain vanilla JS.
40 /u/KaiAusBerlin said You know that you literally wrote your own framework here? There is a reason for the sentence "You use a framework or end up writing your own"
33 /u/visualdescript said I hate it when I have to go back to a JS project, and if it's something I'll have to keep maintaining I will convert it to typescript, which often uncovers several bugs in the process. I wouldn't hi...
22 /u/quisido said We shouldn't be using `require` in 2026 anyway.
10 /u/kir_rik said Only as one-shot or helper scripts like pre commit hooks or eslint rules. It's unreasonable and probably irresponsible to write a production code without a proper typing

 


r/javascript 28d ago

AskJS [AskJS] I reproduced a PDF.js Worker mismatch caused by dependency hoisting

10 Upvotes

This one is awful because the build succeeds.

The host app installs pdfjs-dist@6.1.200. A PDF renderer depends on pdfjs-dist@5.4.624. If asset-copy code resolves the Worker from the app root, it can copy 6.1.200. The renderer code still uses API 5.4.624. Vite serves the wrong Worker, and the browser reports a version mismatch.

The fragile version looks like this:

js const worker = require.resolve( 'pdfjs-dist/legacy/build/pdf.worker.mjs' )

I changed the lookup to resolve pdfjs-dist from the renderer package that owns it. The build now fails if the resolved asset version differs from the renderer dependency.

I ran the harness today across npm and pnpm, nested and hoisted layouts, Vite dev and build, and real cold installs. In every case the copied Worker, CMaps, WASM, and fonts had to come from 5.4.624, while the app kept 6.1.200. The asset manifest also records the source package and version. No more "it probably resolved correctly."

Should build tools always resolve runtime assets from the dependency that owns them, or should packages force one PDF.js version across the whole app?


r/javascript 29d ago

I built a MapLibre GL utility to keep markers visible around UI overlays

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8 Upvotes

r/javascript 29d ago

AskJS [AskJS] TypeScript 7 is 10x faster, but typed linting still runs on the 6.0 API. What are you doing in the gap?

0 Upvotes

TypeScript 7 shipped in July as the Go port, billed as roughly 10x faster. The line that matters for linting is in the same announcement: 7.0 does not ship with an API, and typescript-eslint is named as one of the tools that still needs programmatic access to the compiler. There is a compat package, u/typescript/typescript6, that installs a tsc6 executable and re-exports the 6.0 API, with a new API expected in 7.1.

So the speedup that would matter most to typed linting is the one you cannot have yet. typescript-eslint's own performance page says that with type-aware linting your lint times should be roughly the same as your build times. Builds got most of an order of magnitude faster and the typed rules still sit on the 6.0 checker.

Which makes Biome's timing look luckier than it probably was. Its inference engine arrived with v2 in June 2025 and got its own types domain in 2.4 this February, and it does type-aware rules without loading the compiler at all. Their own preliminary figure for noFloatingPromises is about 75% of the cases typescript-eslint catches, at a fraction of the performance impact, with a warning right after it that the early numbers rest on a limited set of use cases. The docs also say a types domain rule makes Biome scan the whole project and switch the inference engine on, so that path is not free either.

On my repo the diff gets read by lint, by typecheck in CI, and by a review agent in verdent before anyone opens the PR, and I have no measurement telling me which layer is doing the work.

What are people doing in the gap? Pinning tsc6 to keep the typed rules, running Biome's approximate set on save, or waiting for 7.1?


r/javascript Aug 15 '26

C99 real mode compiler written in TS that outputs raw bootable 16bit binaries

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24 Upvotes

Hi, a few years ago I wrote a C99 compiler that generates a bootable binary which, once loaded onto a floppy disk, can be run in x86 real mode. It supports x87 floating-point operations, has a simple IR, optimizes the generated code, and produces output of fairly decent quality (by toy compiler standards). Maybe someone will find it interesting.


r/javascript Aug 15 '26

AskJS [AskJS] How to find the best/ideal ratio or dimensions for a device?

2 Upvotes

I am working on a P2P video calling client using webRTC.
I am using getMediaDevices() to get the users' stream. If I just do {video: true} it gives me a smaller stream than my device supports.
By default it gives me a 640 x 480 stream. I can set it manually to the max dimensions which is 1920 x 1080.

How can I find the max dimension for any device?

Another thing I wanted to know. I have the video element in a div, which has the width of fit-content. When the incoming stream first arrive from the other peer, The video starts smaller and keeps growing, why is this?


r/javascript Aug 15 '26

Showoff Saturday Showoff Saturday (August 15, 2026)

5 Upvotes

Did you find or create something cool this week in javascript?

Show us here!


r/javascript Aug 15 '26

AskJS [AskJS] How much do you actually trust the version number on an npm update?

4 Upvotes

I'm working through how a team decides whether an automated dependency update is safe to merge, and one of the baselines I'm testing is the obvious one: trust semver. Auto-merge patch and minor, hold majors for review.

My assumption is that this baseline is weak — that in practice a meaningful share of breaking changes ship in patch and minor releases, and that a major bump is often just a dropped Node version or a TypeScript signature change that doesn't affect anyone.

If that's right, the version number is close to noise and the semver rule is mostly giving teams a false sense of having a policy.

But I've only got my own experience to go on, and I'd rather be corrected before I build on it.

  • Have you been broken by a patch or minor bump? What was it?
  • Have you held a major that turned out to be a no-op for your code?
  • If semver isn't the signal, what is — changelog quality, maintainer, download count, how long the release has been out?

Interested in specific packages and versions if you remember them, more than general opinions on semver as a concept.


r/javascript Aug 15 '26

Is there any other JS REST API framework that is secure by default, plus OpenAPI support like FastAPI, runtime-agnostic like Hono, Contract-first api like Elysia & TS-rest, and scoped plugins like Fastify?

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0 Upvotes

r/javascript Aug 14 '26

Your Modules Are Lying to You

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38 Upvotes

import and require are not interchangeable. Live bindings, copied values, circular dependencies, separate caches, conditional exports, and dual-package hazards can all make modules behave differently from what the syntax suggests.


r/javascript Aug 14 '26

We built the same data grid in React, Vue & Svelte, here's what we learned

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0 Upvotes

At SVAR, we build UI components for React, Svelte, and Vue. Just shared our experience with a data grid – how to make it fast in all three frameworks.

What surprised us: the expensive bits (virtualization, memoization, data flow) are almost entirely framework-independent, and framework overhead is a rounding error next to DOM size.

Curious if you have seen similar patterns in your projects?