JavaScript typeof undefined in class

When I make a class:

class DialogueChoice
{
    constructor(text, resultFunc) //dialogue line text, function to call when selected
    {
        this.integer = 25;
        ...
    }
    test()
    {
        console.log(typeof(this.integer))
    }
}

I get undefined as the type instead of a number when calling test(). Why is this? what am I missing? It happens for the other members as well. As far as I can tell the class is losing all it’s members after the constructor? Trying to print the value results in undefined as well. The issue only occurs when the func is called through pixijs event system. Calling from the main body of the script is fine.

>Solution :

How do you use your class, because to me it seems to work as expected?

class DialogueChoice
{
    constructor(text, resultFunc) //dialogue line text, function to call when selected
    {
        this.integer = 25;
    }
    test()
    {
        console.log(typeof(this.integer))
    }
}

var dc = new DialogueChoice();
dc.test();

When you pass the test method to another function that then calls it, you have to make sure to bind it to the original object that it is attached to. Otherwise the context for that method will be the global object window. Something like this:

someOtherFunction(dc.test.bind(dc));

Alternatively you can wrap it in another function:

someOtherFunction(() => dc.test());