Let’s go step by step through the Syntax in JavaScript.

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✍️ JavaScript Syntax

Syntax = The set of rules that define how JavaScript programs are written and understood.
👉 If grammar is for English, syntax is grammar for code.

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1️⃣ JavaScript Program Structure

• A program is made of statements (instructions).
• Statements are usually written one per line.
• They can end with a semicolon ( ; ) (optional, but recommended).

let x = 5;   // Statement 1
let y = 10;  // Statement 2
let sum = x + y; // Statement 3
console.log(sum); // Output: 15

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2️⃣ Case Sensitivity

• JavaScript is case-sensitive.
• myVar and myvar are different.

let name = "Raj";
let Name = "Kumar";
console.log(name); // Raj
console.log(Name); // Kumar

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3️⃣ Comments

Used to explain code (ignored by the browser).

// Single-line comment

/*
Multi-line
comment
*/

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4️⃣ Identifiers (Names)

• Names for variables, functions, etc.
• Must start with a letter, _, or $.
• Cannot start with a number.

let myName = "Raj";  
let $salary = 5000;  
let _age = 25;

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5️⃣ Variables

Declaring and assigning values:

var oldWay = "not recommended";  
let modernWay = "better";  
const constantValue = 3.14;

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6️⃣ Data Types

let str = "Hello";   // string
let num = 42;        // number
let isTrue = true;   // boolean
let x;               // undefined
let y = null;        // null
let arr = [1, 2, 3]; // array (object)

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7️⃣ Operators

let a = 10, b = 5;
console.log(a + b);  // 15 (Addition)
console.log(a - b);  // 5 (Subtraction)
console.log(a * b);  // 50 (Multiplication)
console.log(a / b);  // 2 (Division)
console.log(a % b);  // 0 (Modulus)

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8️⃣ Control Flow (Conditions & Loops)

if (a > b) {
  console.log("a is bigger");
} else {
  console.log("b is bigger");
}

for (let i = 0; i < 3; i++) {
  console.log(i);
}

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9️⃣ Functions

Reusable code blocks.

function greet(name) {
  return "Hello " + name;
}
console.log(greet("Raj"));

Arrow function (modern):

const add = (x, y) => x + y;
console.log(add(2, 3)); // 5

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🔟 Objects & Arrays

let person = { name: "Raj", age: 20 };  
console.log(person.name); // Raj

let fruits = ["Apple", "Banana", "Mango"];  
console.log(fruits[1]); // Banana

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✅ Summary

JavaScript syntax includes:

• Statements (end with ;)
• Case-sensitive keywords & identifiers
• Comments (//, /* */)
• Variables (var, let, const)
• Data types (string, number, boolean, object…)
• Operators (+ - * / %)
• Control structures (if, else, for, while)
• Functions (function, arrow functions)
• Objects & arrays