Tipos especiales: any, unknown, never, void de TypeScript

Programming with TypeScript offers a more robust development experience thanks to its static typing system. While JavaScript allows for greater flexibility, TypeScript provides additional safety by detecting errors during compilation. Exploring advanced variable types in TypeScript is essential to get the most out of this language and create more robust and maintainable applications.

What are advanced variable types in TypeScript?

After becoming familiar with basic TypeScript types such as string, number and boolean, it is time to explore more advanced types that offer additional functionality. These special types allow us to handle particular situations in our code and are powerful tools when used correctly.

How does the any type work?

The any type is probably the most flexible type in TypeScript, since it allows us to assign any type of value to a variable. To declare a variable of type any, we use the following syntax:

let variableAny: any;

Once declared, we can assign different types of values to it without restrictions:

variableAny = "hello"; // Text stringvariableAny = 42; // NumbervariableAny = true; // Boolean.

It is important to note that using any eliminates the advantages of the TypeScript type system, since we are basically telling the compiler to ignore the type of this variable. For this reason, it is recommended to limit its use to situations where it is really necessary.

What is the unknown type used for?

Type unknown is similar to any, but with a crucial difference: it is safer. A variable of type unknown can receive any value, but we cannot perform operations with it without first checking its type:

let variableUnknown: unknown;
variableUnknown = "hello";// variableUnknown = 42;// variableUnknown = true;
if (typeof variableUnknown === "string") { console.log("Variable unknown is a string:", variableUnknown);}

The main advantage of unknown over any is that it forces us to perform type checks before using the variable, which reduces the possibility of runtime errors.

When to use the never type in functions?

The never type is used for functions that never return a value, usually because:

• They throw an exception
• Have an infinite loop
• They terminate the program

A common case is for functions that throw errors:

function throwError(message: string): never { throw new Error(message);}
// throwError("This is an error");

The never type is particularly useful for handling error cases in complex applications and for ensuring that certain parts of the code never execute normally.

What does the void type represent?

The void type is mainly used for functions that do not return any value, but do terminate their execution normally (unlike never):

function logMessage(message: string): void { console.log(message); // No return}
logMessage("This is a log message");

The function with void type can execute code and terminate normally, but does not return any usable value. It is common in functions that perform some action but do not need to return information.

How to choose the right type for each situation?

Choosing the right type depends on the context and specific needs:

• Use any when you really can't predict the type (although it's best to avoid it when possible).
• Prefer unknown over any when you need flexibility but want to maintain type safety.
• Use never for functions that throw exceptions or never terminate.
• Apply void for functions that perform actions but do not return values.

Constant practice with these types will help you become familiar with their peculiarities and use them effectively in your TypeScript projects.

Understanding these advanced variable types in TypeScript is critical to developing robust and maintainable applications. We invite you to experiment with these concepts, intentionally cause errors, and learn from them. What other TypeScript types would you like to explore? Share your experiences in the comments.