Variables and Data Types

Variables in JavaScript:

In JavaScript, variables are used to store and manage data. They serve as containers that hold values. You can declare variables using three different keywords: var, let, and const. Each has its own characteristics:

var: This was the original way to declare variables in JavaScript, but it has some quirks and is now less commonly used. Variables declared with var have function scope, meaning they are accessible within the function in which they are declared.
let: Introduced in ECMAScript 6 (ES6), let provides block-level scoping. Variables declared with let are limited in scope to the block, statement, or expression where they are defined. This helps prevent unintended variable leakage.
const: Also introduced in ES6, const is used to declare variables that should never be reassigned after their initial assignment. They also have block-level scope, like variables declared with let.

Data Types in JavaScript:

JavaScript supports various data types, each with a specific purpose. Understanding these data types is crucial for effectively working with data in your programs.

String: Strings are sequences of characters enclosed in single or double quotes.
Example:
```
let greeting = "Hello, World!";
```
Number: Numbers can be integers or floating-point numbers.
Example:
```
let age = 30;
let pi = 3.14;
```
Boolean: Booleans represent binary values, either true or false.
Example:
```
let isStudent = true;
```
Array: Arrays are ordered lists of values. They can hold elements of different data types.
Example:
```
let colors = ["red", "green", "blue"];
```
Object: Objects are collections of key-value pairs and are used to represent complex data structures.
Example:
```
let person = {
  name: "Alice",
  age: 25,
};
```
Null: null is a special value that represents the absence of any object value.
Example:
```
let emptyValue = null;
```
Undefined: When a variable is declared but not assigned a value, it is considered undefined.
Example:
```
let notDefined;
```

These data types are the building blocks of your JavaScript programs. Understanding how to use and manipulate them is essential for creating meaningful and functional applications. In the following sections of this module, we'll explore how to work with these data types and variables effectively.

Variables in JavaScript:​

Data Types in JavaScript:​

Variables in JavaScript:

Data Types in JavaScript: