Variables and types

Store values safely with const and let, and understand what JavaScript considers a type.

Beginner 10 min read Lesson 1 of 480 Challenge included

What you will be able to do

Declare variables with const and let
Recognise primitive types
Use template literals

JavaScript has dynamic types: a variable can hold any kind of value. Prefer const by default and use let only when you must reassign.

basics.jsJavaScript

const learner = "Amina";
let streak = 4;

streak = streak + 1;

const greeting = `Welcome back, ${learner}. Streak: ${streak} days.`;
console.log(greeting);

Type	Example	Notes
string	"hello"	Text in quotes or backticks.
number	42, 3.14	One numeric type, including decimals.
boolean	true / false	Result of comparisons.
null	null	An intentional absence.
undefined	undefined	A missing value.
object	{ name: "Amina" }	Collections and complex values.

Your turn

Build a greeting

Easy

Create const name and let points, add 10 to points, then log a template literal with both values.

JAVASCRIPT · starter

const name = "Rafiq";
let points = 40;
// add 10 points and log a greeting

Check your understanding before moving on.

Knowledge checkQuestion 1

Which declaration allows reassignment?

Select an answer to continue

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Next: Functions and scope

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