JavaScript

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JavaScript Advanced

Tagged Template Literals: The Feature Behind Every html`` You've Seen

That html`...` syntax in lit and friends is not magic - it is a plain JavaScript feature you can use to build an XSS-safe HTML helper in fifteen lines.

May 16, 2024 2 min 2,386 Read →

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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 1,629 Read →

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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 4,799 Read →

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JavaScript Beginner

Serialize an Entire Form in One Line with FormData

new FormData(form) reads every field in one call, posts natively with fetch, and Object.fromEntries turns it into JSON. You may never write form.elements loops again.

Apr 25, 2024 2 min 3,258 Read →

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JavaScript Beginner

The <dialog> Element Probably Replaces Your Modal Library

Focus trapping, Escape to close, a backdrop, top-layer stacking above every z-index - the native dialog element does all of it with zero JavaScript dependencies.

Apr 16, 2024 2 min 823 Read →

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JavaScript Intermediate

Let Users Paste Screenshots Straight into Your App

Ctrl+V with an image on the clipboard fires a paste event carrying a real File object. Ten lines of code turn any form into a screenshot-friendly uploader.

Apr 12, 2024 2 min 4,952 Read →

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JavaScript Advanced

Do the Boring Work When the Browser Is Bored: requestIdleCallback

Analytics batching, prefetching, cache warming - none of it should compete with user interaction. requestIdleCallback runs your low-priority work in the gaps.

Apr 6, 2024 2 min 4,135 Read →

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JavaScript Advanced

Catching DOM Changes You Didn't Make: MutationObserver in Practice

When a third-party script injects, moves or mangles your markup, you cannot patch their code - but you can watch the DOM itself and react the instant it changes.

Mar 28, 2024 2 min 1,676 Read →

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JavaScript Intermediate

Infinite Scroll Without a Single Scroll Listener

Scroll listeners fire hundreds of times per second and need throttling, math and luck. IntersectionObserver watches a sentinel element and calls you exactly when it matters.

Mar 19, 2024 2 min 1,720 Read →

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JavaScript Beginner

The One-Line Browser Trick That Makes Any Page Editable

Type document.designMode = "on" in the console and the entire page becomes editable like a document. Absurdly useful for copy reviews, screenshots and layout testing.

Mar 12, 2024 2 min 5,149 Read →

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JavaScript Beginner

Stop Parsing Query Strings by Hand

Splitting location.search on & and = is a bug farm: encoding, arrays and empty values all break it. URLSearchParams and the URL API handle every edge case and read better.

Mar 5, 2024 2 min 1,791 Read →

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JavaScript Beginner

console.log Is the Least Interesting Thing About the Console

console.table, console.groupCollapsed, console.time and a few DevTools-only helpers like $0 and copy() will change how you debug. Most of them are one keystroke away and almost nobody uses them.

Mar 1, 2024 2 min 2,600 Read →