Glossary term
What is single-threaded? Meaning for developers
JavaScript has exactly one call stack, so it can run exactly one line at a time. Everything that looks parallel is queued around that one thread.
Learn it properly · JavaScript CoreLesson 1: How JS Works: The Execution ContextEverything in JavaScript happens inside an execution context. How the global one is created — memory phase first, then code phase — and why that order explains almost everything that follows.