35. What is a type alias in TypeScript and when would you use one?

What is a type alias in TypeScript and when would you use one?

A type alias in TypeScript is a way to give a name to a type. This can be particularly useful when you want to simplify complex types or to make your code more readable. Type aliases are created using the type keyword followed by the alias name and an assignment to the actual type.

Example

type Point = {
  x: number;
  y: number;
};

function logPoint(point: Point) {
  console.log(`Point coordinates are (${point.x}, ${point.y})`);
}

const point: Point = { x: 10, y: 20 };
logPoint(point);

In the above example, Point is a type alias for an object type with x and y properties. Using a type alias helps in making the function logPoint easier to understand and use.

When to Use Type Aliases

• Complex Types: When dealing with complex types such as objects with many properties or nested types, a type alias can simplify the definition and usage.
• Reusable Types: If a particular type is used in multiple places throughout your code, defining it once as a type alias can prevent redundancy and make maintenance easier.
• Readability: Using descriptive type aliases can make your code more readable by providing meaningful names to complex types.

Type aliases are versatile and can be used with any TypeScript type including primitives, unions, intersections, and even other type aliases. However, they cannot be used to create new types like classes or interfaces can.