What are the best practices for using union types in TypeScript?

What are the best practices for using union types in TypeScript?

When using union types in TypeScript, it's important to ensure clarity and maintainability. Here are some best practices:

1. Use descriptive type names.
2. Limit the number of types in a union to avoid complexity.
3. Utilize type guards to handle different types safely.
4. Document your union types for better understanding.

Can you give an example of a union type?

Sure! Here's a simple example:

type Shape = 'circle' | 'square' | 'triangle';
function drawShape(shape: Shape) {
    // Implementation here
}

In this example, the Shape type can only be one of the three specified string literals.

What are type guards and how do I use them?

Type guards are functions or expressions that allow you to narrow down the type of a variable within a conditional block. For example:

function isCircle(shape: Shape): shape is 'circle' {
    return shape === 'circle';
}

You can use this function to check if a shape is a circle before performing circle-specific logic.

Are there any performance considerations with union types?

Yes, while union types are powerful, they can introduce complexity in type checking, which may impact performance in large codebases. It's best to use them judiciously and keep unions manageable.