JavaScript Visual Lab
Interactive visual explanations for core JavaScript concepts. Step through code execution and watch memory models update in real-time.
JS Visual Playground
Interactive code editor & visual debugger. Step through execution line-by-line, inspect scope variables & heap memory, and test async promises.
Event Loop Visualizer
Visualize the Call Stack, Web APIs, Microtask Queue, and Macrotask Queue in real-time.
Promise Execution
See how promise chains execute, resolve, reject, and how errors propagate through catch blocks.
Closure Visualizer
Understand lexical scoping and see how closures actually store variables in memory.
React Fiber Visualizer
Step through initial component tree mount, setState dispatch, workInProgress diffing, and commit phase updates.
Browser Rendering Pipeline
Step-by-step visualizer for HTML parsing, CSSOM construction, Layout tree calculation, Painting, and Compositing.
Web Workers & Multi-threading
Visualize structured clone data transfer between main UI thread and background web worker threads.
"Guess the Output" JS Quiz
Interactive quizzes on coercion, scope, and event loop execution order with automated step animations.