How the following challenge is not a constructor function?

One question does have "constructor function" as the correct answer.

So I'm guessing you're asking about the other one that does not. If you compare those two questions, the example code is very similar in structure. Both end where a variable is assigned with a class instance created by calling a constructor. prefaced by the "new" keyword.

But in one question, you are asked to describe the function being called (which begins with a capital letter), and the correct answer is indeed a constructor function.

In the other question, you are asked to describe the variable being assigned (which begins with a lower-case letter), and that variable represents the class instance that is being created.

Here's a generic example:

//             this is the constructor function
//             vvv
var spot = new Dog("Dalmation");
//  ^^^^
//  this is a class instance

Hi there,

This a good question :) Here's an example of an instance and a constructor function. Maybe it will clear some things up

var Person = function(name, occupation) {     //This is the constructor function. By convention the var is capitalize, but it does not have to be for it to work. 
     this.name = name;
     this.occupation = occupation;
}

var mark = new Person("Mark", "Student"); 

The var mark is the instance. It is an instance because the new keyword creates a new object, which allows the constructor function to point to the newly created object here. Hence, it's an instance of the constructor function. The instance is what guide the constructor function, so it will know to point to that object. It can definitely be confusing, but let me know if this make sense.

Steven Parker if you linked the pages, the link gone.

Correct me if I am wrong, but I think this is the quiz question.

Given the following code what is the best way to describe task?

function TodoListItem(description) {     //This is the constructor function
  this.description = description;
  this.isDone = false;
  this.toString = function() {
    return this.description;
  }
  this.markAsComplete = function() {
    this.isDone = true;
  }
}

var task = new TodoListItem("Do the laundry!");     //This is not the constructor function but the instance 

If you compare this to my example above it should show why the var task is not a constructor function. Notice how the new keyword is creating a new object, then the TodoListItem constructor function is invoked. You can tell the difference by looking at each specific part and what it is doing :) Think of the constructor function as the blueprint, and the instance is what we put inside the blueprint. Hope this clear things up, but I can try to break it down another way if needed.