JS Type System vs CLR Type System (inheritance behavior) #284
Description
Hi. I found a weird behavior of ineritance and I don't know if this is the expected behavior or not. The issue is relative to the instanceof operator. When the declaracion/creation is inside a script, all works as I expected:
class A { }
class B extends A { }
const a = new A();
const b = new B();
console.log('typeof a == typeof b:', typeof a == typeof b); // true
console.log('typeof a === typeof b:', typeof a === typeof b); // true
console.log('a instanceof A:', a instanceof A); // true
console.log('a instanceof B:', a instanceof B); // false
console.log('b instanceof B:', b instanceof B); // true
console.log('b instanceof A:', b instanceof A); // true
console.log('B.prototype instanceof A:', B.prototype instanceof A); // true
But when coming from CLR, the behavior is different. I derived the base class from JSObject, because if not, the result is still worst.
class A : JSObject
{
public A()
{
this.ValueType = JSValueType.Object;
this.Value = this;
}
}
class B : A
{
}
And the result is:
var context = new NiL.JS.Core.Context();
context.DefineConstructor(typeof(A));
context.DefineConstructor(typeof(B));
context.DefineVariable("a").Assign(new A());
context.DefineVariable("b").Assign(new B());
var t1 = context.Eval("typeof a == typeof b").Value; // true
var t2 = context.Eval("typeof a === typeof b").Value; // true
var t3 = context.Eval("a instanceof A").Value; // true
var t4 = context.Eval("a instanceof B").Value; // false
var t5 = context.Eval("b instanceof B").Value; // true
var t6 = context.Eval("b instanceof A").Value; // false <-------------- why ?
var t7 = context.Eval("B.prototype instanceof A").Value; // false <---- why ?
Is there a way to change this behavior throw JSObject? Am I wrong? With DefineConstant, obviously, nothing change.
Thank you in advance.