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JavaScript Unique Array Values
Returns a new array with duplicate values removed. The fast version uses a Set for primitives. The deep version supports deduplicating objects by a specific key, making it suitable for deduplicating API results or merged data sets.
JavaScript Web Crypto — AES-GCM Encrypt & Decrypt
Encrypts and decrypts text using AES-GCM (256-bit) via the browser's native Web Crypto API — no external library needed. A random 96-bit IV is generated per encryption and prepended to the output so decryption can recover it. Suitable for encrypting sensitive data client-side before storage.
JavaScript Intersection Observer (Lazy Load / Reveal)
Uses the IntersectionObserver API to trigger a callback when elements enter the viewport. The reveal pattern adds a visible class to animate elements as they scroll into view. The lazyLoad pattern loads images on demand by swapping data-src to src. Much more performant than scroll event listeners.
JavaScript Slugify String
Converts any string into a URL-safe slug: lowercases it, replaces accented characters with ASCII equivalents, strips all non-alphanumeric characters (except hyphens), and collapses multiple hyphens into one. Ideal for generating URL slugs from blog titles, product names, or user input.
JavaScript Async Sleep / Delay
Returns a Promise that resolves after a given number of milliseconds. Use with await to pause async functions without blocking the main thread. More readable than nested setTimeout callbacks and composable with other async utilities.
Python flatten — Recursively Flatten Nested Lists
Yield every leaf from arbitrarily-nested lists/tuples. Strings are intentionally treated as atomic (we don't want to "flatten" "hi" into ["h", "i"]).
JavaScript Throttle
Ensures a function is called at most once per specified time interval, no matter how many times the trigger fires. Ideal for scroll listeners, mousemove handlers, and window resize events where you need regular updates but not every single frame.
JavaScript Debounce
Delays invoking a function until after a specified wait time has elapsed since the last time it was called. Essential for search inputs, resize handlers, and any event that fires rapidly — prevents excessive function calls and improves performance.
JavaScript Copy Text to Clipboard
Copies a string to the system clipboard. Uses the modern navigator.clipboard.writeText API (requires HTTPS or localhost) and falls back to the deprecated document.execCommand approach for older browsers or non-secure contexts. Returns a Promise so you can show success/error feedback.
JavaScript DOM Ready Helper
Runs a callback when the DOM is fully parsed and ready, without waiting for images or stylesheets. Works whether called before or after DOMContentLoaded has already fired — unlike a bare addEventListener which misses the event if the DOM is already ready when the script runs.
JavaScript String Template Tag — SQL / HTML Sanitiser
A tagged template literal that automatically escapes interpolated values, preventing SQL injection (server-side) or XSS (client-side) from untrusted input. The html tag HTML-encodes values; the sql tag parameterises values and returns a { text, values } tuple ready for a parameterised query driver.
JavaScript Download File from Client
Programmatically triggers a file download from a Blob, File object, or plain text/JSON string without a server round-trip. Creates a temporary anchor element with a download attribute and revokes the object URL after use to prevent memory leaks. Supports custom filenames and MIME types.
JavaScript Detect Mobile / Device Type
Detects whether the user is on a mobile, tablet, or desktop device. The navigator.userAgentData API (Chromium) is preferred for its structured data; falls back to a User-Agent regex for Safari and Firefox. Useful for conditional rendering, touch event handling, and analytics segmentation.
JavaScript Shuffle Array (Fisher-Yates)
Randomly shuffles an array in-place using the Fisher-Yates algorithm, which produces a uniformly random permutation. Widely considered the correct way to shuffle — avoids the bias inherent in sort(() => Math.random() - 0.5). Returns the same array reference after shuffling.
JavaScript Observable / Reactive State
A minimal reactive state container. Wrap any object with observable() and it returns a Proxy that notifies subscribers whenever a property is set. subscribe() registers a listener that receives the changed key and new value. A lightweight alternative to MobX or Vue's reactive() for small-scale reactivity needs.
JavaScript Format File Size
Converts a raw byte count into a human-readable string with the appropriate unit (B, KB, MB, GB, TB). Uses 1024-based (binary) units by default or optionally 1000-based (SI) units. Useful for upload progress indicators, file browsers, and storage dashboards.
JavaScript UUID v4 Generator
Generates a RFC 4122 compliant version-4 UUID. Uses crypto.randomUUID() in modern environments (Node 14.17+, all modern browsers) and falls back to a Math.random()-based implementation for older runtimes. The fallback is suitable for non-security-critical IDs such as UI element keys and local correlation IDs.
Bash Detect Whether Running as Root
Several scripts must run as root (or refuse to). EUID is more reliable than `whoami == root` because sudo without -E may change one but not the other.