ACARA Digital Technologies Years 9–10 Definitions Worksheet: Modular and Object-Oriented Programming (JavaScript) (Modules 728–742)
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Key terms
Write what each term means, in your own words.
1
modify code
2
OOP
3
class Dog
4
student.age = 16
5
greet() { ... }
6
new ClassName(arguments)
7
this.name
8
object.property
9
deposit(amount) { this.balance += amount; return this.balance; }
10
this.balance += amount
Answer Key
ACARA Digital Technologies Years 9–10 · Modules 728–742 · Student wording will vary for definitions
1modify code — Read the code and predict its output, change one small part at a time, then re-run your tests after each change to check that nothing else broke.
2OOP — Object-oriented programming: building a program from objects that bundle related data with the code that uses it, modelling real things and reusing a blueprint.
3class Dog — A blueprint for dogs. An object like Rex is made from it. Properties are its data (nouns like name) and methods are its actions (verbs like bark).
4student.age = 16 — Assigning to object.property with = changes an existing property or adds a new one if it is not there yet. Reading a property that does not exist gives undefined.
5greet() { ... } — A method is a function stored as an object property. Write it inside the object, then call it with a dot and brackets: person.greet().
6new ClassName(arguments) — Creates an object from a class and passes the arguments to the constructor. Store it in a variable, e.g. const rex = new Dog('Rex', 3). Leaving out new causes an error.
7this.name — Inside a class, this means the object being worked on, so this.name is that object's own name property. Leaving out this causes a ReferenceError.
8object.property — Reads a property of an object, like rex.age. To change it, assign a new value: rex.age = 4. Each object keeps its own values.
9deposit(amount) { this.balance += amount; return this.balance; } — A class method takes a parameter (amount) and uses return to give back a value worked out from the object's properties, such as the new balance.
10this.balance += amount — A method line that updates the object's own property, so its state changes each time the method is called. Calling deposit(50) twice adds 50 twice.