Understand JavaScript Deeply
Step through code execution, watch the Call Stack grow and shrink, see variables hoist — all in real time.
Start with How JS Runs →Learning Path
How JavaScript Runs
Full-Spectrum JS Playground
Execute any custom JavaScript code line-by-line. Visualize the entire JS runtime: Call Stack, Memory Space (GO/AO/Heap), Scope Chain, Closures, this Binding, and Event Loop in real time.
Scope Chain
Lexical Scope & Lookup
Master variable resolution through the Scope Chain. Step through nested Activation Objects (AO) and Global Object (GO) lookup rules.
Understanding this
Binding Rules
Demystify the most confusing keyword in JS. See how this is bound in different contexts: default, implicit, explicit (call/apply/bind), and new.
Closures
Lexical Environment
Understand how functions remember their outer scope. Visualize closure environments and see why they're the foundation of functional patterns.
Prototype Chain
Object Inheritance
Explore how prototype chains work under the hood. See how property lookup traverses the chain and how inheritance is implemented.
Class & Inheritance
ES6 Syntax Sugar
See how ES6 class syntax maps to prototype-based inheritance. Understand super, extends, and the difference from classical OOP.
Event Loop
Async & Task Queue
Visualize how JS handles async code with the Event Loop, Call Stack, Micro-task Queue, and Macro-task Queue in real time.