2️⃣ ✍️ TypeScript Syntax, Variables & Operators – Master the Fundamentals in 2025

🧲 Introduction – Why Learn TypeScript Syntax & Variables?

Mastering TypeScript syntax and variable declarations is the first step toward writing clean, scalable code. By introducing strong typing and modern constructs like let, const, and advanced operators, TypeScript reduces bugs and improves developer productivity. This article covers everything you need to confidently write and manage variables and expressions in TypeScript.

🎯 In this guide, you’ll learn:

• TypeScript’s syntax structure and how it differs from JavaScript
• The proper way to declare variables using let, const, and var
• How TypeScript enforces type safety during variable assignments
• All essential operators for computation and logic

📘 Topics Covered

✍️ TypeScript Basic Syntax Overview

TypeScript uses the same syntax as JavaScript but adds types:

let username: string = "Vaibhav";
let age: number = 25;

🔹 Statements end with a semicolon
🔹 Type annotations follow :
🔹 Blocks are defined using {}
🔹 Functions and classes follow JavaScript structure

💡 Declaring Variables in TypeScript

TypeScript supports 3 keywords: var, let, and const.

✅ Example:

var oldWay = "Can be redeclared";
let newWay = "Block scoped";
const fixedValue = "Cannot change";

🔐 Type Annotations with Variables

let city: string = "Pune";
let isActive: boolean = true;
let salary: number = 50000;

⛔ Type mismatch example:

let score: number = "100"; // ❌ Error – Expected number

📌 let vs const in TypeScript

• let is used for variables whose values may change
• const is used for immutable bindings

Example:

let count = 1;
count = 2; // ✅ allowed

const pi = 3.14;
pi = 3.1416; // ❌ Error: cannot assign to const

🧮 TypeScript Operators

TypeScript supports all common JavaScript operators with full type checking.

🔢 Arithmetic Operators

let sum = 10 + 5;
let product = 4 * 3;

🤝 Comparison Operators

let isEqual = (10 === 10); // true

⚙️ Logical Operators

let result = true && false; // false

🧮 Other Operators

📌 Summary – Recap & Next Steps

Understanding TypeScript syntax, variable declaration, and operator usage is foundational to writing robust, type-safe applications. By enforcing strict typing and offering modern constructs like let and const, TypeScript encourages clean and maintainable code from the start.

🔍 Key Takeaways:

• Use let and const over var for better scope management
• Type annotations prevent type errors during compile time
• Operators behave like JavaScript, but with strict type checks

⚙️ Real-World Relevance:
Writing correct syntax and using variables properly is vital in all TypeScript projects, from small scripts to enterprise-grade applications.

❓ FAQ – TypeScript Syntax & Variables

❓ What’s the difference between var, let, and const in TypeScript?

✅ var is function-scoped and can be redeclared. let is block-scoped and reassignable. const is also block-scoped but immutable.

❓ Do I always need to specify a type in TypeScript?

✅ No. TypeScript uses type inference, but it’s recommended for clarity and error checking.

❓ Can I change the value of a const array or object?

✅ You can modify the contents of an array or object declared with const, but you cannot reassign the variable itself.

❓ How does TypeScript help with operator usage?

✅ TypeScript provides compile-time checks that ensure operators are used with correct operand types (e.g., not adding a number to a boolean).