There is one subtle logic bug. function hasDuplicate(nums) { const seen = new Set(); for (const n of nums) { if (seen.has(n)) { return false; } seen.add(n); } return true; } console.log(hasDup…
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## [Spot the bug - #85](https://forum.kirupa.com/t/spot-the-bug-85/682592)
Hey folks, I’m working on a search-as-you-type picker in a React app and I’m trying to keep it snappy on low-end laptops while the dataset can spike from 5k to 200k items. Right now we do fuzzy matching + scoring on eac…
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## [How do you debug weird caching when users swear they refreshed?](https://forum.kirupa.com/t/how-do-you-debug-weird-caching-when-users-swear-they-refreshed/682566)
Yo Kirupa folks, I’m migrating a frontend from REST to a CDN-fronted GraphQL API and I keep getting “it’s fixed for me but not for them” reports even after people hard refresh, and the failure mode feels like some combo …
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## [Spot the bug - #83](https://forum.kirupa.com/t/spot-the-bug-83/682565)
DOM bug, pretty sneaky. const items = document.querySelector('.todo li'); console.log(items.length); Reply with what is broken and how you would fix it.
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## [How do you stop tests from randomly failing when a component measures the DOM?](https://forum.kirupa.com/t/how-do-you-stop-tests-from-randomly-failing-when-a-component-measures-the-dom/682547)
Yo Kirupa folks, I’m trying to make our React component tests less flaky and I think I’m shooting myself in the foot with DOM measurement + state updates (it fails like 1/20 runs, usually in CI). import { useLayoutEffec…
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## [Spot the bug - #82](https://forum.kirupa.com/t/spot-the-bug-82/682546)
Color helper has one tiny bug. function normalizeHex(hex) { const value = hex.startsWith('#') ? hex : '#' + hex; return value.slice(0, 6); } console.log(normalizeHex('#12abef')); Reply with what is broken and how …
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## [A tiny responsive form grid that keeps error messages from wrecking card layout](https://forum.kirupa.com/t/a-tiny-responsive-form-grid-that-keeps-error-messages-from-wrecking-card-layout/682528)
Yo folks, I’m wiring up a checkout form that sits inside responsive “card” tiles, and the annoying failure mode is when a single validation message gets long and the whole grid jumps or the card overflows on mobile. .ca…
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## [Spot the bug - #80](https://forum.kirupa.com/t/spot-the-bug-80/682521)
Can you spot the form bug? \ \Email\ \ \ \ document.querySelector('form').addEventListener('submit', (e) =\> { …
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## [Spot the bug - #81](https://forum.kirupa.com/t/spot-the-bug-81/682526)
Quick one: event handling bug here. const button = document.querySelector('#save'); button.addEventListener('click', saveForm()); function saveForm() { console.log('saved'); } Reply with what is broken and how you w…
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## [How do you draw the line between a Web Worker and the main thread without a message spaghetti mess?](https://forum.kirupa.com/t/how-do-you-draw-the-line-between-a-web-worker-and-the-main-thread-without-a-message-spaghetti-mess/682504)
What’s up everyone? I’m trying to move some heavier work (filtering/sorting a big dataset plus a little formatting) into a Web Worker so the UI stays snappy, but I keep tripping over where state should live and how chatt…
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## [Spot the bug - #79](https://forum.kirupa.com/t/spot-the-bug-79/682502)
Find the bug in this animation loop. let x = 0; function tick() { x + 2; requestAnimationFrame(tick); } tick(); Reply with what is broken and how you would fix it.
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## [Spot the bug - #78](https://forum.kirupa.com/t/spot-the-bug-78/682484)
Can you spot the form bug? \ \Email\ \ \ \ document.querySelector('form').addEventListener('submit', (e) =\> { …
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## [JS Quiz: Hard: Node list snapshot vs live collection](https://forum.kirupa.com/t/js-quiz-hard-node-list-snapshot-vs-live-collection/682358)
Assuming this runs in a browser, what logs? const ul = document.createElement('ul'); ul.innerHTML = '\A\\B\'; document.body.appendChild(ul); const staticList = ul.querySelectorAll('li'); const liveList = …
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## [How do you stop CSS variants from leaking across components without going full BEM?](https://forum.kirupa.com/t/how-do-you-stop-css-variants-from-leaking-across-components-without-going-full-bem/682467)
Yo Kirupa folks, I’m refactoring a little design system at work and I’m trying to keep component styles predictable while still letting state variants (loading/disabled/error) stack without surprises. .card { --bg: whit…
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## [Spot the bug - #77](https://forum.kirupa.com/t/spot-the-bug-77/682465)
Quick one: event handling bug here. const button = document.querySelector('#save'); button.addEventListener('click', saveForm()); function saveForm() { console.log('saved'); } Reply with what is broken and how you w…
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## [✨ Archive Spotlight: Modifying How Corners Look](https://forum.kirupa.com/t/archive-spotlight-modifying-how-corners-look/682466)
If you’re trying to make corners look less like default AI mush and more intentional, this kirupa piece is a nice quick read. It walks through the small visual tweaks that make a surprisingly big difference without turn…
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## [A tiny rAF spring helper that stays dependency-free](https://forum.kirupa.com/t/a-tiny-raf-spring-helper-that-stays-dependency-free/682453)
Hey folks, I’m cleaning up a UI micro-interaction at work and I’m trying to keep the bundle lean, so I replaced a small animation lib with a tiny spring. The failure mode I hit before was accidental double-imports from d…
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## [Spot the bug - #76](https://forum.kirupa.com/t/spot-the-bug-76/682452)
Find the bug in this animation loop. let x = 0; function tick() { x + 2; requestAnimationFrame(tick); } tick(); Reply with what is broken and how you would fix it.
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## [How do you keep global keyboard shortcuts from breaking text input and accessibility?](https://forum.kirupa.com/t/how-do-you-keep-global-keyboard-shortcuts-from-breaking-text-input-and-accessibility/682435)
What’s up everyone? I’m wiring up global keyboard shortcuts for a web app (think cmd+k, /, esc) and I’m trying to do it without wrecking normal typing in inputs, contenteditable, or screen reader flows. Right now it fee…
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## [Spot the bug - #75](https://forum.kirupa.com/t/spot-the-bug-75/682434)
Yo folks, I’m wiring up theming in a small dashboard and I wanted one place to own color state so components don’t drift. The failure mode I keep hitting is mutable shared refs: one widget tweaks a palette and suddenly t…
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## [Spot the bug - #74](https://forum.kirupa.com/t/spot-the-bug-74/682419)
There is one subtle logic bug. function hasDuplicate(nums) { const seen = new Set(); for (const n of nums) { if (seen.has(n)) { return false; } seen.add(n); } return true; } console.log(hasDup…
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## [Spot the bug - #73](https://forum.kirupa.com/t/spot-the-bug-73/682400)
Quick one: event handling bug here. const button = document.querySelector('#save'); button.addEventListener('click', saveForm()); function saveForm() { console.log('saved'); } Reply with what is broken and how you w…
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## [A tiny string pipeline that keeps highlights stable while truncating](https://forum.kirupa.com/t/a-tiny-string-pipeline-that-keeps-highlights-stable-while-truncating/682398)
Hey everyone, I’m wiring up a search results list and I’m trying to keep my string formatting predictable without mutating the same object in three different places. The failure mode I kept hitting was highlight ranges d…
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## [A tiny share or copy helper that degrades nicely without extra deps](https://forum.kirupa.com/t/a-tiny-share-or-copy-helper-that-degrades-nicely-without-extra-deps/682384)
What’s up everyone? I’m wiring up a “Share” button for a docs-ish web app, and I’m trying to keep the UX decent without dragging in a big dependency or shipping a bunch of edge-case UI. The tradeoff is obvious: feature-r…
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## [Spot the bug - #72](https://forum.kirupa.com/t/spot-the-bug-72/682381)
There is one subtle logic bug. function hasDuplicate(nums) { const seen = new Set(); for (const n of nums) { if (seen.has(n)) { return false; } seen.add(n); } return true; } console.log(hasDup…
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## [How do you keep retry with backoff from turning into a thundering herd?](https://forum.kirupa.com/t/how-do-you-keep-retry-with-backoff-from-turning-into-a-thundering-herd/682360)
Yo folks, I’m wiring up a fetch wrapper that retries with exponential backoff + jitter, and I’m trying to keep it fast under load. My failure mode right now is when the API has a brief outage, a bunch of callers all retr…
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## [Spot the bug - #71](https://forum.kirupa.com/t/spot-the-bug-71/682359)
Can you spot the form bug? \ \Email\ \ \ \ document.querySelector('form').addEventListener('submit', (e) =\> { …
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## [JS Quiz: Easy: Async return in finally](https://forum.kirupa.com/t/js-quiz-easy-async-return-in-finally/682256)