What are `unknown` and `never` types in Typescript?

Dear TypeScript Enthusiasts,

Today, we embark on a journey to unravel TypeScript's well-guarded secrets: the unknown and never types. Let's delve into these intriguing types and explore how they can revolutionize your coding arsenal.

The unknown Type: Taming the Unknown

Imagine standing at a crossroads, unsure of which path to take. TypeScript faces a similar situation when it encounters data of uncertain type during compile-time. Enter the unknown type—a versatile and adaptable solution that allows TypeScript to handle uncertainty gracefully.

Usage: Here's an example illustrating the unknown type:

In this scenario, safelyParseJSON accepts a JSON string of unknown structure. It tries to parse it and gracefully handles parsing errors. The unknown type acknowledges that we can't be certain about the shape of the data, ensuring type safety.

Real-World Use-Cases:

Dynamic Data Processing:

When dealing with data from external sources like APIs or user inputs, its structure might vary. unknown is your shield against unpredictable data.

Integration with JavaScript Libraries:

1. When working with JavaScript libraries that don't provide type information, unknown helps maintain type safety.

The never Type: Embracing the Unreachable

Introduction: Now, let's shift our focus to a different aspect of TypeScript—the never type. It represents values that will never occur. It's like the "point of no return" in your code, signaling situations that should never happen.

Usage: Consider a function that throws an error and never returns:

In this case, never signifies that this function will never produce a value—it always throws an error, halting the program's execution.

Real-World Use-Cases:

• Guard Clauses:

When implementing exhaustive type checks using union types, never can be employed to indicate that certain branches of code should never be reached.

• Infinite Loops and Unreachable Code:

In scenarios like a server continuously listening for requests, functions that run infinitely can be marked with the never type to indicate they never return.

Real-World Examples Reimagined

• Dynamic API Responses:

• Ensuring Exhaustive Checks:

• Infinite Loop:

These examples demonstrate how unknown and never types empower TypeScript to handle uncertainty, and impossible scenarios, and ensure code safety and expressiveness.

In conclusion, these TypeScript types are your trusty companions in navigating the complexities of dynamic data and unreachable code. Embrace them, and you'll wield even greater power in your TypeScript adventures.

Keep nurturing your TypeScript skills, one insight at a time. Should you seek enlightenment or have questions, feel free to reach out. Your feedback continues to shape our journey.

Happy coding!