Introduction to Objects I 28/33

Passing Objects into Functions
In addition to making arrays of Objects, we can use objects as parameters for functions as well. That way, these functions can take advantage of the methods and properties that a certain object type provides.
To see an example, take a look at the console. In addition to our Person constructor we have introduced a new function, ageDifference(line 9). This function takes two Personobjects as parameters, and returns the difference in age between the two people.
Notice we would be in trouble here if we tried to call ageDifference and passed in strings instead of people, because strings don't have an age property. But because we know from our constructor that all Person objects will have an age property, we can pass anyPerson into ageDifference. We must be careful not to pass anything but Personobjects into ageDifference.

Instructions

We have created two example people, aliceand billy. Complete line 17 by callingageDifference and saving the result in our global diff variable.

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Hint

We can call ageDifference just as we might call any other function. And it will take two parameters, the names of our two objects.

                                                                       // Our person constructor

                                                                          function Person (name, age) {

                                                                          this.name = name;

                                                                          this.age = age;

                                                                            }

                                                                  // We can make a function which takes persons as arguments

                                                              // This one computes the difference in ages between two people

                                                                        var ageDifference = function(person1, person2) {

                                                                        return person1.age - person2.age;

                                                                          }

                                                                      var alice = new Person("Alice", 30);

                                                                      var billy = new Person("Billy", 25);

                                                            // get the difference in age between alice and billy using our function

                                                                var diff =  ageDifference(alice,billy);