UD5 Toolkit
Error.cause Property Demo - Online Chained Errors
Create errors with the cause option and see chained error objects. Learn error wrapping for better debugging.
Tag: JavaScript Tools - Debug & Convert
29+ toolsBrowser Console Simulator - Online Practice JavaScript Logging
Type JavaScript expressions and see output like a real browser console. Supports console.log, error, warn. Use for quick testing without DevTools.
Text Scramble Effect - Online Decoding Animation
Animate text that looks like it's being decoded or scrambled before settling on the final word. Copy the JS snippet.
JavaScript Regex Cheatsheet - Online Interactive Pattern Reference
Interactive cheatsheet for JavaScript regular expressions with live examples. Click any token to see its explanation and test it on sample text immediately.
Frontend JS Library Vulnerability Scanner - Online Check Version
Paste a URL or HTML to detect known vulnerable JavaScript library versions. Quick security audit. Client‑side only.
PDF Script Inspector - Online See Embedded JavaScript
Drop a PDF and extract any embedded JavaScript or form actions. Check for malicious code. Privacy‑friendly analysis.
Auto‑Resize Textarea Demo - Online Grow with Content
A textarea that expands in height as you type. See the implementation and copy the code. No library needed.
Intl API Explorer - Online Format Numbers, Dates, Lists
Explore all Intl APIs: NumberFormat, DateTimeFormat, RelativeTimeFormat, ListFormat. See outputs for any locale. Powerful i18n.
JavaScript Memory Heap Checker - Online performance.memory
Display used/total/limit JS heap size using performance.memory. Take snapshots and see growth. Simple memory leak detection.
structuredClone() Playground - Online Deep Copy Tester
Input any JavaScript object and see if structuredClone can deep‑copy it. Compare with JSON.parse/stringify. Learn transferables.
Bookmarklet Code Builder - Online Convert JS to Bookmark
Write a JavaScript snippet and get a ready‑to‑drag bookmarklet link. With minification and encoding. Easy browser tools.
Custom Event Dispatcher Demo - Online Send & Listen
Create and dispatch custom events with detail. Listen on other elements. Understand pub/sub pattern in vanilla JS.
Web Animations API Sandbox - Online JS Animation Editor
Write JavaScript using element.animate() and see the result in a live preview. Compare with CSS keyframes. Debugger included.
JavaScript Syntax Validator - Online Check Errors
Paste JavaScript and catch syntax errors instantly with line numbers. Lightweight pre‑commit check. Local.
JavaScript Proxy Playground - Online Observe Object
Apply a Proxy to an object and see the get/set traps log fired in real time. Understand metaprogramming. Local.
Babel Config Generator - Online Presets & Plugins
Choose Babel presets (env, React, TypeScript) and plugins. Get a clean babel.config.json to transpile your code. Local tool.
JavaScript Live Tester - Online Run & Debug Snippets
Write JavaScript code and see the output or console.log results immediately. Safe iframe sandbox. For quick experiments.
Event Loop Visualizer - Online See Call Stack & Microtask Queue
Watch a simulation of how the JavaScript event loop handles synchronous code, microtasks, and macrotasks. Learn async.
Text to Unicode Escape Sequence Converter - Online
Convert any text into JavaScript‑style \uXXXX escape sequences and vice versa. Handles emojis. Useful for i18n development.
Ternary Operator Playground - Online Explore ? : in JavaScript
Type any condition and see the result of the ternary operator. Understand truthy/falsy values. Quick learning tool.
JavaScript Beautifier & Formatter - Online JS Code Styler
Make your JavaScript code more readable with this online beautifier. Format and indent JS automatically. Works entirely in your browser, protecting your code privacy.
Generator Function Explorer - Online Step by Step
Write a generator function and step through it with next(). See values and done state. Understand iterators.
Keyboard Event Viewer - Online key, code, keyCode Inspector
Press any key to see the complete KeyboardEvent properties: key, code, keyCode, modifiers. Indispensable for game & shortcut developers.
Bookmarklet Generator - Online Convert JS to Browser Bookmark
Paste any JavaScript snippet and get a ready‑to‑drag bookmarklet link. Minify and encode automatically. Pure client.
Fullscreen API Tester - Online Request & Exit Demo
Test the Fullscreen API: request fullscreen on a colored div, detect changes, and copy the JavaScript boilerplate.
JavaScript Type Checker - Online Typeof & Instanceof Sandbox
Paste any JavaScript expression and see its evaluated type and value. Understand JS coercion and type quirks. Educational.
JavaScript Keycode Finder - Online Keyboard Event Tool
Press any key to see the corresponding JavaScript event key, code, and keyCode. An essential debugging tool for front-end developers handling keyboard input.
Online Code Minifier - JS & CSS Compression Tool
Minify JavaScript and CSS code to reduce file size for production. Remove whitespace and comments instantly. Run locally, your code stays private.
Promise State Viewer - Online Check Resolve & Reject
Create promises that resolve or reject after a delay. See state changes and chain .then/.catch. Debug async code.