Vue props type with TypeScript

This is so-called constructor type.

More strictly, this property can appear in following different ways:

• as a generic function (): T returning the specified type T;
• as a generic constructor new (...args): T & object, creating the object of specified type T with additional properties from type object.

The Object type satisfies the second variant, i.e. it's a class with some constructor property. It has the following definition (from lib.es5.d.ts):

interface Object {  /** The initial value of Object.prototype.constructor is the standard built-in Object constructor. */  constructor: Function;  // some more properties here}

Note that this is the most general constructor possible, and so it could potentionally return any possible value. So the transpiler tells you exactly that - "you have a class whose constructor returns any".

Seems that you could just use User as property type. Since it's a class too, I suppose, it will have the signature of new (...args) => User, so it would infer exactly the type you need.

upd: missed the interface definition in the question. Well, if there's no reason to make it a class instead, the proper typing (and usage) seems to be the function: () => User, not Object.