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Not Bound

Methods in JavaScript are not bound to their object by default (as they are in languages like Python and Go). So if you use a method as a "callback" function, you may run into issues with the this keyword:

const user = {
  name: "Lane",
  sayHi() {
    console.log(`Hi, my name is ${this.name}`);
  },
};

user.sayHi();
// Hi, my name is Lane

const sayHi = user.sayHi;
sayHi();
// TypeError: Cannot read properties of undefined (reading 'name')

This happens a lot when passing a method as a callback function to another function:

const user = {
  firstName: "Lane",
  lastName: "Wagner",
  getFullName() {
    return `${this.firstName} ${this.lastName}`;
  },
};

function getGreeting(introduction, nameCallback) {
  return `${introduction}, ${nameCallback()}`;
}

console.log(user.getFullName());
// Lane Wagner
console.log(getGreeting("Hello", user.getFullName));
// TypeError: Cannot read properties of undefined (reading 'firstName')

If you want to use a method as a callback function, you'll need to bind it to the object using the bind method:

const boundGetFullName = user.getFullName.bind(user);
console.log(getGreeting("Hello", boundGetFullName));

Assignment

Fix the bug on line 19 so that this correctly references the scope of the campaign object.