不知道为什么我会收到这个 TypeError

Question

I'm using classes and objects to create a list of stuff in javascript (I'm pretty new to programming). Now, I thought I had this right but for some reason it's throwing a

"Uncaught TypeError: courseList.calculateValue is not a function at assignment.js:27"

Can't figure out why this isn't working. Please help! Here's my code:

Answer 1

You have an object courseList with nested array courses, that actually contains objects of class Course.

courseList doesnt have this methods, because they were defined inside Course class. To execute this methods you need to do courseList.courses[0].calculateValue() and courseList.courses[1].calculateValue()

Answer 2

Looks like you're calling calculateValue() on an object that is not a Course object.

In your case you need to do courseList.courses[0].calculateValue() to calculate the value of the first course. And likewise you can do it for other courses by changing the index.

Longer explanation

courseList (badly named) is an object with just one property called courses .

This property has a value which is a list of Course objects. So in order to call methods from the Course class on these objects you need to access them by first accessing the value of the course property in courseList and then choosing one of the courses from the list using an index like courseList.courses[1]

courseList.courses[1] is now a Course object so you can call calculateValue() and printSummary() on it

Side Note

Your console.log() statement on line 28 won't print your results (even when you make the fix above) since printSummary doesn't return anything. You don't need to call console.log() on it at all, since printSummary handles the printing within it