Written guides
JavaScript Execution Guides
Deep, spec-grounded explanations of how JavaScript actually runs — each guide pairs a precise mental model with runnable traces you can open in the visualizer.
- JavaScript runtime guideRead the full guide →
How JavaScript Executes Code: From Global Code to Function Return
A precise mental model for JavaScript execution contexts, function calls, lexical environments, and the call stack.
- JavaScript declarations guideRead the full guide →
JavaScript Hoisting: Declarations, Initialization, and the Temporal Dead Zone
A practical explanation of why var, let, const, and function declarations behave differently before their source lines run.
- JavaScript scope guideRead the full guide →
How the JavaScript Scope Chain Works
Understand lexical scope, identifier lookup, shadowing, and closures through small JavaScript traces you can run.
- JavaScript this guideRead the full guide →
Understanding this in JavaScript
A call-site-first explanation of how JavaScript decides what this refers to — default, implicit, explicit, and new binding — with runnable examples.
- JavaScript closures guideRead the full guide →
How Closures Work in JavaScript
Understand how a function keeps a live connection to the environment it was created in, with runnable examples covering state, loops, and private data.