? JavaScript Syntax Overview

JavaScript syntax defines the rules for writing valid code. Understanding it helps you write programs that the JavaScript engine can interpret correctly.

Key Syntax Elements

1. Statements

• A statement performs an action and ends with a semicolon ; (optional but recommended).

let x = 5;console.log(x);

2. Variables

• Declared using var (old), let, or const.

let name = "Alice";const pi = 3.14;

3. Comments

• Single-line: // comment

• Multi-line: /* comment */

4. Data Types

• Number, String, Boolean, Object, Array, Function, null, undefined, Symbol, BigInt.

5. Operators

• Arithmetic: +, -, *, /, %

• Assignment: =, +=, -=

• Comparison: ==, ===, !=, !==, >, <

• Logical: &&, ||, !

6. Functions

function greet(name) {  return `Hello, ${name}!`;}

7. Control Structures

• Conditional: if, else if, else, switch

• Loops: for, while, do...while, for...of, for...in

8. Blocks

• Group of statements inside { }

if (x > 10) {  console.log("Large number");}

9. Expressions

• Produce values:

let total = 5 + 10; // 15

10. Semicolons

• Optional in many cases due to Automatic Semicolon Insertion (ASI), but recommended for clarity.

Example: Basic Syntax in Action

// Declare variableslet age = 30;const name = "John";// Functionfunction sayHello(user) {  if (user) {    return `Hello, ${user}!`;  } else {    return "Hello, guest!";  }}// Use the functionconsole.log(sayHello(name));console.log(sayHello());

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