Adding JavaScript to a web page

JavaScript can be added to an HTML file using the script tag:

<script src="script.js"></script>

Comments in JavaScript

Single-line comments in JavaScript start with //, while multi-line comments start with **/***and end with */.

// This is a single-line comment

/*
This is a multi-line comment
*/

Printing to the console

You can print to the console in JavaScript using the console.log() function:

console.log("Hello, world!");

Variables in JavaScript

Variables in JavaScript can be declared using let, const, or var.

let x = 5; // a variable declared with let can be reassigned
const y = 10; // a variable declared with const cannot be reassigned
var z = 15; // a variable declared with var has function scope

Declaring and assigning variables

Variables in JavaScript can be declared and assigned in the same line:

let x = 5;

Arithmetic Operators

JavaScript supports arithmetic operators such as addition, subtraction, multiplication, division, and modulus:

let x = 5;
let y = 10;
let z = x + y; // addition
let a = x - y; // subtraction
let b = x * y; // multiplication
let c = y / x; // division
let d = y % x; // modulus

Unary Operators

Unary operators are operators that work with only one operand. JavaScript supports several unary operators, such as increment, decrement, and negation: