What is TypeScript? What is it used for?

In today’s fast-evolving digital world, JavaScript is the primary language used to create dynamic web applications. However, writing JavaScript code can sometimes lead to errors, and detecting these issues early in the development process may not always be possible. This is where TypeScript comes into play, aiming to revolutionize how JavaScript code is written.

Offering a refined and advanced coding paradigm, TypeScript is a superset of JavaScript that helps identify potential issues early on. This minimizes error risks, resulting in robust, reliable development and an improved workflow. If you want to learn how this compiled programming language unleashes its power while providing better tools at every scale, keep reading.

What is TypeScript?

TypeScript is a superset of JavaScript that adds optional static typing and advanced features. Developed by Microsoft and released in 2012, TypeScript has quickly gained popularity in the web development community, becoming the 4th most loved technology (1). It was created to overcome some limitations of JavaScript, especially around strong typing errors that are hard to catch during development.

For example, consider the following JavaScript code:

function add(a, b) {
 return a + b;
}
let result = add(10, "20"); // No error, but result is "1020" instead of 30

This code defines a dynamic add function where the types of a and b are not enforced. Passing a string instead of a number does not cause an error, but leads to unexpected behavior by concatenating the values as strings.

With TypeScript, developers can specify types for variables, function parameters, and return values, catching type-related errors during development:

function add(a: number, b: number): number {
 return a + b;
}
let result = add(10, "20"); // Error: Argument of type 'string' is not assignable to parameter of type 'number'

Here, a and b are explicitly defined as numbers. Passing a string causes a compile-time error, providing early feedback to prevent potential bugs.

What Can You Do With TypeScript?

TypeScript extends JavaScript and enhances the developer experience. It allows adding type safety to projects and supports various other features like interfaces, type aliases, abstract classes, function overloading, tuples, and generics. For example, when calling any Contentful API, you receive an object containing the needed data. Interfaces ensure that this object has the correct data types and required properties. Interfaces are useful for defining request bodies, response objects, or function parameters.

The syntax of an interface looks like this:

interface interfaceName {
 variableOne: type;
 variableTwo: type;
}

Using this, you can define a profile interface with properties like name and social.

Another notable feature is Literal Types. Individually, they might seem limited, but combined, they can be very powerful.

For instance:

let social: "twitter" = "harshil1712";

Here, the variable social has the literal type "twitter". While not very useful alone, combining literal types with function parameters is powerful:

function greet(message: string, name: "Alice" | "Bob") {
 //...
}
greet("Hello", "Alice");
greet("Hey", "Bob");
greet("Hey", "Max"); // Error: Argument of type '"Max"' is not assignable to parameter of type '"Alice" | "Bob"'.

This function only accepts "Alice" or "Bob" as the second parameter, helping create functions that accept a specific set of known values.

What Are the Components of TypeScript?

TypeScript consists of three main layers, each with sublayers and components:

Language Elements: Includes syntax, keywords, and type annotations.

• TypeScript Compiler (TSC): Converts TypeScript code into equivalent JavaScript, performs parsing, and type checking. Browsers don’t support executing TypeScript directly, so the code is compiled to JavaScript. The compiler supports ES6 by default and can target various module formats like SystemJS and AMD.
• Language Service: Provides information to editors and tools for features like refactoring and IntelliSense. It offers an additional layer around the core compiler to support standard editor operations such as code formatting, highlighting, statement completion, and signature help.

What Is TypeScript Used For?

TypeScript’s static type system helps catch syntax errors and type mismatches early in development, saving time in the long run.

Type annotations make code more maintainable, especially important in large codebases. TypeScript offers advanced tools like type checking, code completion, and refactoring, resulting in better software development experiences. These features improve code quality, making it more reliable and less prone to errors.

Who Uses TypeScript?

TypeScript is used worldwide by major companies and projects, including:

• Google: Uses it for products ranging from Duo to Google Cloud Functions and Google Cloud Platform tools.
• Microsoft: Employs TypeScript in Visual Studio Code, TypeScript Language Services, Azure Functions, and more.
• Airbnb: Develops its React Native apps and backend services with TypeScript.
• Pinterest: Builds web and Android apps on the TypeScript framework.
• Netflix: Uses TypeScript for its Android app and backend services.

Why Choose TypeScript?

Built on top of JavaScript, TypeScript fills in the gaps and provides better tools for developers at every scale. It is both easy to use and efficient compared to competitors.

Ease of Use: If you know at least some JavaScript, starting with TypeScript requires minimal effort. All TypeScript code is compiled to JavaScript for execution. Conversely, any JavaScript (.js) file can be renamed to TypeScript (.ts) for compilation with other TypeScript files.

Portability: TypeScript code compiles to JavaScript, which runs anywhere JavaScript does—browsers, devices, operating systems—eliminating the need for special runtime environments.

Robust Developer Tooling: TypeScript reduces errors, aids debugging, and improves developer productivity with better tools. TSC runs as a background process supporting compilation and IDE integration, benefiting developers greatly.

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