What is TypeScript? 💡

TypeScript (TS) is a programming language created by Microsoft that extends JavaScript by adding strict typing. This makes the code more predictable and reduces the number of errors. 🚀

TypeScript is compiled into regular JavaScript, which allows it to be used in any project where JS works.

Why study TypeScript? 🎯

• Safety: typing prevents errors.

• Readability: the code becomes clearer.

• ES6+ support: new JavaScript functions work without problems.

• Compatibility: can be used in any JS project.

How to install TypeScript? 💻

To work with TypeScript, you will need:

• ✅ Node.js (to run the code). You can download it from official website.

• ✅ TypeScript Compiler. You can install it via the terminal:

npm install -g typescript

How to check if TypeScript is installed? 🛠

Open the terminal and enter:

tsc --version

If TypeScript is installed, its version will appear. Now you can write code! 🚀

TypeScript Syntax Basics 📚

1. Variables 📦

In TypeScript, variables are declared with types.

Example of declaring variables:

let name: string = "Alice";   // Line
const age: number = 25;       // Number
let pi: number = 3.14;        // Floating point number
let isStudent: boolean = true; // Boolean value

console.log(`Name: ${name}, Age: ${age}, Pi: ${pi}, Student: ${isStudent}`);

2. Data output 📤

To output data to the console, use console.log().

Example:

console.log("Hello, TypeScript!");

3. Conditional operators (if...else) 🧐

Allow the program to make decisions.

Example:

let age: number = 20;

if (age >= 18) {
    console.log("You're an adult!");
} else {
    console.log("You're still a child.");
}

4. Loops (for, while) 🔄

Loops allow you to perform the same action multiple times.

Example:

for (let i: number = 1; i <= 5; i++) {
    console.log(i);
}

5. Functions 📐

Functions help to structure the code.

Example:

function square(x: number): number {
    return x * x;
}

console.log("Square of the number 5:", square(5));

Simple projects in TypeScript 💡

1. Random number generator 🎲

The program generates a random number from 1 to 100.

function getRandomNumber(): number {
    return Math.floor(Math.random() * 100) + 1;
}

console.log("Random number:", getRandomNumber());

2. Even numbers filter 🔢

The function filters even numbers from the array.

function filterEvenNumbers(numbers: number[]): number[] {
    return numbers.filter(num => num % 2 === 0);
}

console.log(filterEvenNumbers([1, 2, 3, 4, 5, 6]));

3. Checking the string for palindromes 🔄

The program checks whether the string is a palindrome.

function isPalindrome(str: string): boolean {
    const cleanStr = str.toLowerCase().replace(/[^a-z0-9]/g, '');
    return cleanStr === cleanStr.split('').reverse().join('');
}

console.log("Is 'racecar' a palindrome?", isPalindrome("racecar"));

4. Counting words in a line 🔢

The function counts the number of words in a string.

function countWords(text: string): number {
    return text.split(" ").length;
}

console.log("Number of words in 'Hello, TypeScript world!':", countWords("Hello, TypeScript world!"));

5. Fibonacci sequence 🔢

The program calculates the first 10 numbers of the Fibonacci sequence.

function fibonacci(n: number): number[] {
    let fib: number[] = [0, 1];
    for (let i = 2; i < n; i++) {
        fib.push(fib[i - 1] + fib[i - 2]);
    }
    return fib;
}

console.log("The first 10 Fibonacci numbers:", fibonacci(10));

Conclusion 🎉

TypeScript is a powerful development tool that makes code more reliable. We have analyzed its basics: variables, input/output, conditions, loops and functions. Now you can write your first programs! 🚀

The more you practice, the better your code becomes. Experiment, try new tasks and master programming! Good luck learning TypeScript! 😊