How to define an array of strings in TypeScript interface?

In TypeScript, there are multiple ways to define string arrays. However, when defining within interfaces, we typically use type annotations to explicitly specify that the array elements are strings. Here are two common approaches:

Approach 1: Using string[]

In this approach, we directly use string[] to annotate the type, indicating that the interface property is an array of strings.

typescript
interface IUserNames {
    names: string[];
}

// Usage example
const userNames: IUserNames = {
    names: ["Alice", "Bob", "Charlie"]
};

This approach is straightforward and clearly indicates that names is a string array.

Approach 2: Using Array<string>

This approach uses the generic form Array<string> to define a string array. It is functionally equivalent to the previous method but differs slightly in syntax.

typescript
interface IUserNames {
    names: Array<string>;
}

// Usage example
const userNames: IUserNames = {
    names: ["Alice", "Bob", "Charlie"]
};

This approach can be more readable in certain cases, especially when the array element type is complex (e.g., when elements are other interfaces or type aliases).

Summary

Regardless of which approach you choose, maintaining code consistency is crucial. Within a team, you should consistently use one approach for defining array types to reduce the burden of understanding and maintenance. In both examples above, we define an interface IUserNames containing a property names, which is a string array. This ensures type safety and leverages TypeScript's type checking capabilities.