TypeScript and JavaScript are the most popular programming languages widely used in web development. If you are a web developer, you must have heard about them.

Do you know the difference between JavaScript and TypeScript, or have you ever been confused about choosing between them? If yes, we have covered the difference between them, which one you should choose between them, and how to migrate from JavaScript to TypeScript.

JavaScript

Initially, in 1994, JavaScript was developed for the Netscape browser to add interactivity to web pages. After that, in 1997, the first standardized version of JavaScript was launched.

In the starting phase, JavaScript was used to add interactivity to the web pages. For example, to add a click event, form submission event, etc. So, it was used with HTML and CSS and became a fundamental scripting language for them.

Nowadays, JavaScript is also used for backend development. For example, NodeJS is used to create the backend of the web applications.

In simple terms, JavaScript is a cross-platform programming language, which can be used to develop the frontend and backend of the application.

Features of JavaScript

Here are some basic features of JavaScript.

• Dynamic Typing − JavaScript variables don’t have fixed types. So, it provides the flexibility in assigning the values to the variables.

• First-Class Functions − In JavaScript, functions can be expressions. So, it can be assigned to a variable, passed as arguments, and returned from other functions.

• Prototypal Inheritance − JavaScript supports prototype-based inheritance, which can be achieved by modifying the object prototypes. However, it also supports class-based inheritance.

• Asynchronous Programming − JavaScript supports asynchronous programming with callbacks, promises, and async/await.

• Cross-platform support − JavaScript is supported by all modern web browsers and other platforms. It is also used to develop the front end and backend of web applications. So, it is a platform-independent programming language.

Example

In the code below, the add() function takes two numbers as an argument. In the function body, we sum the values of the parameters ‘a’ and ‘b’ and use the ‘return’ keyword to return the summation of both parameters.

// JavaScript example: Adding two numbers
function add(a, b) {
    return a + b;
}
console.log(add(5, 10)); // Output: 15

The output of the above example code is as follows –

15

TypeScript

TypeScript is very similar to JavaScript, and it has almost the same syntax as JavaScript. In 2012, Microsoft created TypeScript as an open-source project to solve the issues faced by developers while using JavaScript. So, TypeScript contains all the features that JavaScript has and contains some extra features to solve additional issues of typing.

TypeScript has static typing which is more useful in large projects in which multiple developers are working together. Whenever you compile the TypeScript code, it compiles the code in JavaScript, and then you can use NodeJS to run the compiled TypeScript code.

Features of TypeScript

Here are some features of TypeScript, which are not available in JavaScript.

• Static Typing − TypeScript allows you to specify types for each variable, function parameter, and return value. This feature helps in catching errors at compile time.

• Interfaces − TypeScript is an object-oriented programming language, and it contains the interfaces to define the structure of objects that help in improving code readability and maintainability.

• Classes and Inheritance − TypeScript supports classes and classical inheritance, making it easier to create complex structures.

• Compatibility − TypeScript is compatible with all versions of JavaScript.

• JavaScript Features − TypeScript is a superset of JavaScript. So, you can use all JavaScript features, methods, libraries, etc. in TypeScript.

Example

In the code below, we have defined the ‘number’ type for the function parameters, which was not there in the JavaScript code. However, both code produces the same output.

// TypeScript example: Adding two numbers
function add(a: number, b: number): number {
    return a + b;
}
console.log(add(5, 10)); // Output: 15

On compiling, it will generate the following JavaScript code.

// TypeScript example: Adding two numbers
function add(a, b) {
    return a + b;
}
console.log(add(5, 10)); // Output: 15

The output of the above example code is as follows –

15

Key Differences Between JavaScript and TypeScript

The main difference between TypeScript and JavaScript is typing, as JavaScript has dynamic typing and TypeScript has static typing. However, we have covered some more differences between them in the table below.

When to Use JavaScript?

JavaScript can be used in various situations, and here are some of them.

• Smaller Projects − If you want to create smaller projects like static company or personal portfolio, you may use JavaScript.

• Quick Prototyping − If you want to create a quick prototype of the application, you can use JavaScript instead of TypeScript. However, you can migrate JavaScript to TypeScript later.

• Learning Curve − JavaScript is easier for beginners to pick up due to its simpler syntax and lack of strict typing requirements.

When to Use TypeScript?

TypeScript is well-suited for various situations:

• Large Projects − When you are creating large or real-time projects, you should use TypeScript. In large projects, multiple developers work together. So, TypeScript makes it easier for them to know variable type, return type of function values, etc.

• Code Maintainability − Makes maintaining and refactoring code easier with static typing and interfaces.

• Error Detection − Allows for catching errors at compile-time rather than runtime, leading to more reliable code.

• Compatibility − If you are already working with JavaScript libraries, TypeScript can be gradually introduced, providing a smooth transition.

Both JavaScript and TypeScript are the most popular programming languages but can be used in various situations. JavaScript is beginner-friendly and can be used for prototyping applications. While TypeScript can be used for large real-time projects.