Browser APIs

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JavaScript Beginner

Generate and Download Files in the Browser: Blob + download

CSV exports, JSON backups, generated reports - the browser can create files and hand them to the user without the server ever touching the data.

Jul 14, 2025 2 min 1,516 Read →

W

JavaScript Advanced

Why "👨‍👩‍👧".length Is 8, and How to Count What Users See

String length counts UTF-16 code units, not characters - so emoji truncation splits families into corpses. Intl.Segmenter counts graphemes, words and sentences correctly.

Jun 23, 2025 2 min 1,236 Read →

"

JavaScript Beginner

"1 item" vs "2 items": Stop Writing That Ternary

Intl.PluralRules knows every language's plural categories and Intl.ListFormat writes "a, b, and c" correctly - two tiny APIs that end string-building guesswork.

Jun 14, 2025 2 min 2,439 Read →

N

JavaScript Intermediate

navigator.onLine Lies - Build Offline Detection That Doesn't

onLine only knows if there is a network interface, not whether the internet works. Real offline handling means verified checks and a retry queue for failed writes.

May 5, 2025 2 min 1,816 Read →

M

JavaScript Advanced

Measure Real User Performance with PerformanceObserver

Lighthouse tells you about your machine. PerformanceObserver tells you about your users - long tasks, slow interactions and layout shifts, from the field, in a few lines.

Apr 26, 2025 2 min 1,411 Read →

R

JavaScript Intermediate

ResizeObserver: Components That Respond to Their Own Size

Window resize listeners cannot see a sidebar collapsing or a panel being dragged wider. ResizeObserver watches the element itself - the JS half of container-based design.

Mar 16, 2025 2 min 589 Read →

B

JavaScript Intermediate

Build a "Quote This" Feature with the Selection API

That floating "tweet this quote" button on Medium-style sites is the Selection API plus one event. Here is the whole thing, popover positioning included.

Mar 7, 2025 2 min 616 Read →

S

JavaScript Beginner

Stop Using Math.random() for IDs: crypto.randomUUID()

Math.random-based IDs collide more than you think and are predictable by design. The browser ships a real UUID generator and a cryptographic random source - both one-liners.

Feb 26, 2025 2 min 3,105 Read →

Y

JavaScript Intermediate

Your Tabs Can Talk to Each Other: BroadcastChannel

Log out in one tab, stay logged in at the other five? BroadcastChannel syncs state across tabs in three lines - and the storage event covers the legacy cases.

Feb 21, 2025 2 min 2,594 Read →

R

PHP Advanced

Real-Time Updates with Plain PHP: Server-Sent Events

WebSockets need infrastructure. Polling hammers your server. SSE streams live updates over normal HTTP with a PHP file and the built-in EventSource API - reconnection included.

Nov 10, 2024 2 min 1,920 Read →

F

JavaScript Beginner

Format Currencies and "1.2K" Counts Without a Library

Intl.NumberFormat handles currencies, compact notation, percentages and units in the user's locale - the kind of formatting everyone installs a package for.

May 12, 2024 2 min 1,685 Read →

R

JavaScript Intermediate

Responsive JavaScript Without Resize Listeners

Checking window.innerWidth on every resize event is wasteful and drifts out of sync with your CSS. matchMedia gives JavaScript the same breakpoints CSS uses, with change events.

May 3, 2024 2 min 4,864 Read →