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Weak Types in Interfaces

Weak Types in Interfaces

Learn how weak types in TypeScript offer flexibility for defining and validating data structures without strict type enforcement.

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Introduction to weak types

When we define an interface where all of its properties are optional, this is considered to be a weak type. In other words, we have defined an interface, but none of the properties of the interface are mandatory.

Let’s see what happens if we create a weak type and then try to bend the standard type rules as follows:

// Interface `IWeakType` defines the structure of a weak type object with optional properties `id` and `name`
interface IWeakType {
  id?: number;
  name?: string;
}
// `weakTypeNoOverlap` is a variable that is assigned an object that does not match the structure defined by `IWeakType`
// The object has a `description` property, which is not part of the `IWeakType` definition
let weakTypeNoOverlap: IWeakType = {
  description: "a description",
};
Weak types in interfaces

  • We define an interface name IWeakType ...