Language and Runtime Internals

A lexer groups characters into tokens such as identifiers, numbers, and punctuation.

An interactive concept flow for how a parser turns tokens into structure, from its assumptions through the main operation and boundary checks.

Follow the key state changes and boundary checks involved in how a parser turns tokens into structure.

Bytecode is a compact instruction representation designed for a virtual machine rather than one physical processor.

A just-in-time compiler translates code while a program runs.

Follow the key state changes and boundary checks involved in when a runtime compiles hot code.

A function call transfers control while preserving enough state for the caller to resume.

The heap holds objects whose lifetimes are not tied to one simple lexical scope.

An interactive concept flow for heap allocation and garbage collection, from its assumptions through the main operation and boundary checks.

An event loop repeatedly selects ready work and runs callbacks or tasks.

Explain the model, execution steps, complexity, and limits of async code still runs on an event loop.

Determine whether a string can be segmented into dictionary words.