How to get callback to work with “this” in class scope [duplicate]

Answer 1

You can use an anonymous function like this:

// it will show "undefined" because "this" scope changes to window
funWithCallBack(testClass.show); 

to this:

// anonymous function to use the right object for the method
funWithCallBack(function() {
    testClass.show()
}); 

---

Your problem occurs because when you pass testClass.show as the callback, it just gets the function reference and there is no association with testClass any more. But, you can create a temporary function that binds them together using .bind(), but it isn't supported in some older browsers which is why I generally just use the anonymous function.

The .bind() implementation would look like this:

// use .bind() to make sure the method is called in the right object context
funWithCallBack(testClass.show.bind(testClass));