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Lexical scope, declarations, references, receivers, prototypes, promises, modules, equality, and language-level debugging.
Practice items tagged with JavaScript Language Fundamentals.
Explains call-site-dependent this binding and compares wrapper, bind, and arrow-function fixes.
Traces synchronous throws and promise rejections through chains, awaits, missing returns, and detached work.
Relates JavaScript classes to prototype-based delegation while preserving the useful semantics class syntax adds.
Compares JavaScript declarations through scope, initialization, redeclaration, reassignment, and practical default choices.
Designs explicit ESM boundaries with focused exports, controlled side effects, and dependency direction that supports safe bundling.
Diagnoses aliasing and shallow-copy mistakes, then restores explicit state ownership and immutable update boundaries.