java script Chapter2

🧩 Chapter 2: Variables, Data Types, and Operators

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🔹 1. Variables

Used to store data values.

Syntax:

let name = "John";
var age = 18;
const PI = 3.14;

• var → old, function-scoped
• let → block-scoped
• const → for constants (cannot be changed)

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🔹 2. Data Types

Primitive Data Types:

1. String → "Hello"
2. Number → 10, 3.14
3. Boolean → true / false
4. Undefined → variable declared but no value
5. Null → no value
6. Symbol → unique identifier
7. BigInt → very large numbers

Non-Primitive:

• Objects, Arrays, Functions

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🔹 3. Operators

A. Arithmetic Operators

+, -, *, /, %, ++, --

B. Assignment Operators

=, +=, -=, *=, /=, %=

C. Comparison Operators

==, ===, !=, !==, >, <, >=, <=

== compares value
=== compares value + type (strict equality)

D. Logical Operators

&& (AND), || (OR), ! (NOT)

E. String Operators

+ → used for concatenation
Example:

let fullName = firstName + " " + lastName;

F. Ternary Operator

let result = (age >= 18) ? "Adult" : "Minor";

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🔹 4. Type Conversion

Number("10"); // Converts string to number
String(10);   // Converts number to string

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