TypeScript接口描述类

Question

Is there an interface in TypeScript to describe a class declaration?

function module(name: string, classDeclaration: IClass) {
     this.classHash[name] = classDeclaration; //example use of class declaration
}

Answer 1

In JavaScript, there are only functions. The class keyword in TypeScript & EcmaScript 6 is (for the purposes of this question) sugar for creating a constructor function and filling out its prototype. Therefore, a generic interface for a “class” in TypeScript is the same as an interface for any constructor function:

interface Class<T> {
  new (...args: any[]): T;
  prototype: T;
}

Answer 2

Don't name your function module , it is a keyword in TypeScript. AFAIK there is no such interface or class but you can create your own interface IClass which I would strongly recommend.

An example is:

interface IClass {}

class MyClass implements IClass {}
class MySecondClass implements IClass {}

function myModule(name: string, classDeclaration: IClass) {
     this.classHash[name] = classDeclaration; //example use of class declaration
}

myModule("1", MyClass);
myModule("2", new MyClass());
myModule("3", MySecondClass);

Answer 3

No. I would have expected Function (or FunctionConstructor ) to be such an interface, but, no.

What is troubling is that, as expected, in the code below the type returned by typeof is function ... but function (lower case f ) is neither a type nor an interface in Typescript. So the answer has to be no.

"use strict";

class Hello {

    private s: string

    constructor(s: string) {
        this.s= s
    }

    public sayHello() {
        console.log(`Hello ${this.s}`)
    }    
}


function instantiate<T>(clazz: any, name: string): T {
    console.log(`Type of clazz: ${typeof clazz}`)
    return new clazz(name) as any as T
}


instantiate<Hello>(Hello, 'John').sayHello()