JavaScript Syntax

📝 JavaScript Syntax Rules

JavaScript syntax is the set of rules that defines valid JavaScript code. It includes how to write statements, use variables, and structure your code.


// This is a simple JavaScript example
let message = "Hello World!";
console.log(message);

Output:

Hello World!

Key Syntax Rules

🔤

Case Sensitive

JavaScript is case sensitive

let name = "John";
let Name = "Jane"; // Different variable

;

Semicolons

End statements with semicolons

let x = 5;
let y = 10;

🔤

Identifiers

Names for variables and functions

let myVariable = 100;
function myFunction() {}

📝

Keywords

Reserved words with special meaning

let, const, var, function, if, else

🔹 JavaScript Values

JavaScript has two types of values: fixed values (literals) and variable values:

// Fixed values (literals)
10.50    // Number
"Hello"  // String

// Variable values
let x = 10.50;
let name = "Hello";

Output:

x = 10.50
name = "Hello"

🔹 JavaScript Operators

JavaScript uses operators to perform operations on values:

// Arithmetic operators
let sum = 5 + 3;        // Addition
let product = 5 * 3;    // Multiplication

// Assignment operator
let x = 5;              // Assign value

// Comparison operators
let result = (5 > 3);   // Returns true

Output:

sum = 8
product = 15
x = 5
result = true

🔹 JavaScript Expressions

An expression is a combination of values, variables, and operators that computes to a value:

// Expressions
5 * 10              // Evaluates to 50
"Hello" + " World"  // Evaluates to "Hello World"
x * 10              // Evaluates to a number

Output:

50
"Hello World"
(depends on x value)