If you already know javascript, it would be very easy to learn and get started with Typescript. You can take typescript as an extension of javascript with better tooling and more popularity. You can easily convert your previous javascript projects into typescript.

So, are you ready to take one step forward and convert your javascript code into typescript but still unsure where to start? Worry not because in this article we will be going through the whole process step-by-step, showing you how to leverage TypeScript’s static typing to build safer, more reliable components.

Changing the File Extension

We can start with a really simple and easy step by just changing your file extension from .js or .jsx to .ts or .tsx (if the file contains JSX). This will indicate your development environment in that you are working with TypeScript code.

Defining Your Types

In typescript, we have to declare variable types, function parameters, and return values. This is one of the major benefits of TypeScript as it allows type-checking at the compile time.

With this feature, we can intercept and rectify many common errors before deploying the code into a production environment.

For example, consider the following JavaScript function:

Convert Your JavaScript Components into TypeScript

While converting it into TypeScript, we would specify that name should always be a string:

Convert Your JavaScript Components into TypeScript

This prevents any unexpected errors and gives greater control over our code.

Transforming PropTypes to TypeScript Interfaces

As we use PropTypes in javascript to implement specific types for our props. Interfaces serve the same purpose in Typescript.

For example, consider the following JavaScript component with PropTypes:

Convert Your JavaScript Components into TypeScript

Now let’s transform this into TypeScript using interfaces:

Convert Your JavaScript Components into TypeScript

Note: – We can also use optional chaining in using interfaces. e.g;

Convert Your JavaScript Components into TypeScript

React-Specific Typings

When using any javascript library e.g. React, it is important to note that it includes its own unique constructs like hooks and methods, which needs specific type definitions. We have a package known as @types/react that helps us in this aspect and provides us with pre-defined types for these constructs.

For instance, when creating a functional component, we can define the types of props and states as follows:

Convert Your JavaScript Components into TypeScript

Install Type Definitions

Many popular JavaScript libraries have TypeScript definitions available, usually in a package named @types/library-name. E.g. for React (@types/react), for Node.js (@types/node), etc. Make sure to install these types to make full use of TypeScript’s static typing if you are using third-party libraries in your project.

Using Strict Mode

To ensure the highest level of type safety, it is recommended to enable the strict mode to true in your tsconfig.json file. This forces the compiler to perform more rigorous checks, catching potential issues that might otherwise be missed.

Convert Your JavaScript Components into TypeScript

Adopt TypeScript Gradually

We have mentioned earlier that typescript is on top of javascript, always keep this in consideration that moving from javascript to Typescript is a gradual process. As TypeScript supports JavaScript, we can have a combination of both .js and .ts files in our projects. This gives us enough time to convert our components, hence reducing the risk of breaking the working code by introducing bugs or disrupting our workflow.

Compile and Fix Type Errors

After making the necessary changes to the codebase, we need to run the TypeScript compiler (tsc). This will help us in identifying any further issues or type errors in our project.

Working with some new technology can be daunting at times. It’s better to follow a step-by-step process so that the transition from javascript to Typescript can be more smooth and more efficient. The additional safety of TypeScript’s static type checking can save countless hours of debugging down the line. Happy coding!

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