Closures

JavaScript Language Trivia

Beginner JS quirks to predict and explain: `==` vs `===`, hoisting, `this` binding in different call sites, and one quick closure trace.

JavaScript Scope and Closure Code Traces

Six traces covering the `var` loop-closure pitfall, parameter shadowing, IIFE captures, block scope leaks, and `delete` on locals.

JavaScript Closures and Private State Quiz

Build the classic closure patterns: encapsulated counters, lexical-scope inheritance through nested functions, and constructor-level private fields.

JavaScript var Loop Closure: Two Explanations Quiz

The classic var-in-a-for-loop closure trap, explained two ways (shared `i` binding and the IIFE capture fix), plus two companions on the `let` per-iteration binding and a queueMicrotask version of the trap.

JavaScript Inherit x From Function b: Two Approaches Quiz

Make constructor `b` inherit `x` from constructor `a`: parent-constructor call via `Function.prototype.call`, ES6 `extends` + `super`, `Object.create` chaining, and an arrow-vs-constructor explainer.

JavaScript Add-N via Currying: Two Approaches Quiz

Two seeded ways to build an `adder(n)` that adds `n` to its argument (closure-returning-function and `Function.prototype.bind`), plus two companions on three-arg currying and a generic curry helper.