JavaScript

📦 Variables and data types

Store information with let and const, and learn the fundamental data types.

What you'll learn

Declare variables with let and const and decide which one to use depending on whether the value is reassigned.
Distinguish the primitive types (number, string, boolean, null, undefined) and inspect them with typeof.
Tell undefined apart from null and explain the temporal dead zone (TDZ) of let/const.

Practice this module in the app

DevPath is a hands-on course: you read the theory here; in the app you put it into practice with exercises that really run, offline.