JavaScript Basics: How Variables, Data Types, and Operators Work

A beginner-focused tutorial published on DEV Community introduces core JavaScript concepts including variables, data types, and operators. The guide explains the differences between var, let, and const, using a bottle analogy to clarify how const locks a name to a reference rather than freezing the value it holds. It also covers hoisting, describing how var declarations are lifted and pre-filled with undefined, while let and const remain in a Temporal Dead Zone until their declaration line is reached. The article outlines JavaScript's two type families — primitive and reference — and flags the well-known typeof null bug as a permanent language quirk. Readers are advised to default to const, use let only when reassignment is needed, and avoid var in modern code.