This TypeScript code
class A {
private a1;
public a2;
}
compiles to this JavaScript code
class A {
}
That’s because properties in JavaScript start extisting only after they have some value. You have to assign the properties some value.
class A {
private a1 = "";
public a2 = "";
}
it compiles to
class A {
constructor() {
this.a1 = "";
this.a2 = "";
}
}
Still, you cannot get the properties from mere class (you can get only methods from prototype). You must create an instance. Then you get the properties by calling Object.getOwnPropertyNames()
.
let a = new A();
let array = return Object.getOwnPropertyNames(a);
array[0] === "a1";
array[1] === "a2";
Applied to your example
class Describer {
static describe(instance): Array<string> {
return Object.getOwnPropertyNames(instance);
}
}
let a = new A();
let x = Describer.describe(a);