JavaScript Basics: Variables, Data Types, and Operators

JavaScript variables, data types, and operators are foundational to writing code and creating dynamic web applications. This tutorial will guide you through these essentials, explaining how to store and manipulate values in JavaScript.

1. Declaring Variables

JavaScript has three main keywords to declare variables: `var`, `let`, and `const`.

let: Used to declare variables that can change later.
const: Declares variables with values that should not change.
var: Older keyword, now less commonly used in modern JavaScript.

Example:

JavaScript Code

let name = "Alice"; // a variable that can be changed
const birthYear = 1990; // a constant that cannot be changed

2. Data Types in JavaScript

JavaScript supports various data types, including:

String: Text data, defined using single (`'`) or double (`"`) quotes.

JavaScript Code

let greeting = "Hello, world!";

Number: Numerical data, including integers and decimals.

JavaScript Code

let age = 25;

Boolean: Represents true or false values.

JavaScript Code

let isStudent = true;

Undefined: A variable that has been declared but not assigned a value.

JavaScript Code

let score; // undefined variable

Null: Represents an empty or unknown value.

JavaScript Code

let emptyValue = null;

3. Operators in JavaScript

Operators allow you to perform actions on variables and values. Here are some common types:

Arithmetic Operators: Used for mathematical calculations.

JavaScript Code

let x = 10;
let y = 5;
let sum = x + y; // addition
let product = x * y; // multiplication

Assignment Operators: Used to assign values.

JavaScript Code

let a = 10;
a += 5; // a = a + 5

Comparison Operators: Compare two values and return true or false.

JavaScript Code

let isEqual = (x == y); // checks if x equals y
let isGreater = (x > y); // checks if x is greater than y

Logical Operators: Used to combine conditions.

JavaScript Code

let isAdult = (age >= 18) && isStudent; // both conditions must be true

4. Working with Strings

Strings are sequences of characters used to represent text.

Concatenation: Combine two strings using `+`.

JavaScript Code

let firstName = "Alice";
let lastName = "Smith";
let fullName = firstName + " " + lastName;

Template Literals: Use backticks and `${}` for embedded expressions.

JavaScript Code

let age = 25;
let message = `I am ${age} years old.`;

Conclusion

These basics of variables, data types, and operators provide a foundation for JavaScript programming. Understanding how to store, manipulate, and evaluate data will help you progress to more complex coding tasks!

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