The working developer's field notes

Useful code.
Explained properly.

A focused library of JavaScript and TypeScript patterns for the details you solve repeatedly—arrays, browser APIs, async flows, validation, and performance.

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FIELD NOTE · 010•••

function debounce(fn, delay) {

let timer;

return (...args) => {

clearTimeout(timer);

timer = setTimeout(

() => fn(...args), delay

);

};

}

Why it matters

Wait until a burst of input settles before running expensive work.

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30documented patterns

4practical categories

100%open-access reference

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Patterns worth keeping close

Selected for broad usefulness, readable implementations, and the kinds of edge cases that show up in production.

10TypeScript

Debounce Function

Delays function execution until after specified idle time, ideal for search input, autocomplete, and form validation

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11TypeScript

Async/Await Error Handler

Simplifies async/await error handling without try/catch blocks, returns [error, result] tuple

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30TypeScript

Generic Memoization Function

Caches function results based on arguments to avoid redundant computations

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Reference library

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11 results

TypeScriptArray Manipulation

Safe Array Item Access

Prevents index out-of-bounds errors when accessing array elements, returns default value for invalid indices

Array ManipulationError PreventionSafe Access

/**
 * Safe array item access (prevents out-of-bounds errors)
 * @param arr Target array
 * @param index Target index

TypeScriptPerformance

Throttle Function

Limits function execution frequency to specified interval, perfect for scroll/resize events and button clicks

PerformanceEvent HandlingThrottle

/**
 * Throttle function implementation
 * @param fn Function to throttle
 * @param delay Throttle interval in milliseconds

TypeScriptPerformance

Debounce Function

Delays function execution until after specified idle time, ideal for search input, autocomplete, and form validation

PerformanceEvent HandlingDebounce

/**
 * Debounce function implementation
 * @param fn Function to debounce
 * @param delay Idle time in milliseconds

TypeScriptLocalStorage

Local Storage with Expiry

Enhanced localStorage with automatic expiry, supports TTL (Time-To-Live) for stored items

LocalStorageCacheExpiry

/**
 * LocalStorage with expiry support
 */
const ExpiryStorage = {

TypeScriptRandom

Generate Random Unique ID

Generates cryptographically secure random IDs with configurable length, ideal for unique identifiers

RandomID GenerationUnique ID

/**
 * Generate random unique ID
 * @param length ID length (default: 16)
 * @returns Random alphanumeric ID

TypeScriptDOM

Smooth Scroll to Element

Smoothly scrolls to a DOM element with configurable offset and behavior

DOMScrollAnimation

/**
 * Smooth scroll to DOM element
 * @param element Target element or selector
 * @param offset Scroll offset in pixels

TypeScriptDevice Detection

Mobile Device Detection

Detects mobile devices (phones/tablets) using user agent string

Device DetectionUser AgentResponsive

/**
 * Detect if user is on mobile device
 * @returns True if mobile device, false otherwise
 */

TypeScriptClipboard

Copy Text to Clipboard

Cross-browser implementation to copy text to clipboard with promise-based API

ClipboardDOMUtility Function

/**
 * Copy text to clipboard
 * @param text Text to copy
 * @returns Promise resolving to true if successful, false otherwise

TypeScriptDOM

Check if Element is in Viewport

Detects if a DOM element is visible in the viewport (fully or partially)

DOMViewportScroll Detection

/**
 * Check if element is in viewport
 * @param element Target element
 * @param fullyInView Check if element is fully visible (default: false)

TypeScriptArray Manipulation

Shuffle Array (Fisher-Yates Algorithm)

Fair and unbiased array shuffling using the Fisher-Yates (Knuth) shuffle algorithm

Array ManipulationRandomAlgorithm

/**
 * Shuffle array using Fisher-Yates (Knuth) algorithm
 * @param arr Array to shuffle
 * @returns New shuffled array (original remains unchanged)

JavaScriptPerformance

Optimized Scroll Event Handling

Combines debounce with requestAnimationFrame for high-performance scroll event handling

PerformanceScrollEvent Handling

/**
 * Optimized scroll event handler
 * @param callback Function to execute on scroll
 * @param delay Debounce delay in milliseconds

Useful code.Explained properly.

Patterns worth keeping close

Debounce Function

Async/Await Error Handler

Generic Memoization Function

Find the pattern you need

Useful code.
Explained properly.