JavaScript vs TypeScript What’s the Difference?

JavaScript and TypeScript are both widely used in web development and they are closely related. The main difference is how they handle data types and errors.

What is JavaScript?

JavaScript is a dynamically typed programming language. We don't need to specify the type of a variable when declaring it. JavaScript is flexible and can run directly in web browsers, which makes it popular for building interactive websites and web applications.

What is TypeScript?

TypeScript is a superset of JavaScript developed by Microsoft. It adds static typing, which allows developers to specify whether a variable should be a number, string, boolean, or another type. This helps developers find errors earlier while writing the code.

example in JavaScript:

let age = 25;
age = "vijay";

This is allowed because JavaScript is flexible with variable types.

In TypeScript:

let age: number = 25;
age = "vijay"; // Error

Here, TypeScript gives an error because age is defined as a number.

Another important difference is that JavaScript can run directly in the browser, while TypeScript needs to be converted into JavaScript before it can run.

In simple terms, JavaScript provides flexibility while TypeScript adds more structure and type safety. JavaScript is often a good starting point for beginners while TypeScript is especially useful for larger and more complex applications where maintaining clean and reliable code is important.

Why Do Developers Use TypeScript?

One major reason developers use TypeScript is to reduce mistakes in large applications.

Imagine a project has thousands of lines of code and many developers are working on it. Without clear information about what type of data a function expects it can become difficult to understand and maintain the code.

TypeScript can make the code easier to understand by clearly defining the expected types.

example:

function add(a: number, b: number): number {
return a + b;
}

Here we can immediately understand that:

a should be a number.
b should be a number.
The function returns a number.

This can make large projects easier to maintain.