Java Reference
In-Depth Information
Quiz Ninja Project
For the quiz project, we're going to replace the main
play()
function of the quiz with a
Game()
constructor function that will create a new
Game
instance every time it's invoked
with the
new
operator. This will allow us to apply in our quiz some of the principles of OOP
covered in this chapter.
The
Game()
constructor function is very similar to the first part of the
play()
function:
function Game(quiz){
this.questions = quiz.questions;
this.phrase = quiz.question;
this.score = 0; // initialize score
update($score,this.score);
// initialize timer and set up an interval that counts
down
this.time = 20;
update($timer,this.time);
this.interval = window.setInterval(
this.countDown.bind(this) ,
↵
1000 );
// hide button and show form
hide($start);
show($form);
// add event listener to form for when it's submitted
$form.addEventListener('click', function(event) {
event.preventDefault();
this.check(event.target.value);
}.bind(this), false);
this.chooseQuestion();
}
The main differences between the
Game()
constructor function and the
play()
function
are:
• The variables
score
and
time
become
this.score
and
this.time
as they
are properties of the
Game
instance.
