Objects

Question 1

What is a method in javascript

Answer 1

Methods are properties that contain a Function() object.

Question 2

Give a constructor example

Answer 2

var Person = function(living,age,gender){
this.living = living;
...
}
var Cody = new Person(true,33,male);

Question 3

What is the Object() object

Answer 3

An empty generic object container

Question 4

What are the two methods of object creation

Answer 4

1) via a custom constructor
var Car = function Car(color);
var redCar = new Car('red');
2) Via the Object() constructor:
var redCar = new Object();
redCar.colorc = 'red';

Question 5

Explain the ‘new’ keyword

Answer 5

When using new, javascript sets the value of ‘this’ to the newly constructed object. And the new object will be returned by default instead of ‘false’.

Question 6

What are the nine native (global) object constructors

Answer 6

Number(), String(), Boolean(), Object(), Array(),Function(), Date(), RegExp(), Error()

Question 7

What are literals

Answer 7

Shortcuts for manufacturing most of the native object values without having to use new Foo() or new Bar().
E.g. var myNumber = new Number(23);
var myNumberLiteral = 23;

var myObject = new Object();
var myObjectLiteral = {};

Question 8

Give an example of a function literal

Answer 8

var myFunction = new Function("x","y","return x*y");
var myFunctionLiteral = function(x,y) {return x*y}

Question 9

Give an example of an array literal

Answer 9

var myArray = new Array('foo','bar');
var myArrayLiteral = ['foo','bar'];

Question 10

What are primitive values?

Answer 10

Values that are simple, irreducible, not made up of other values.

Question 11

How are primitive values stored/copied?

Answer 11

the value is literally copied/stored.

Question 12

How are complex values stored/copied?

Answer 12

by reference.

Question 13

How do you refer to the constructor of an object?

Answer 13

All objects have a constructor property

Question 14

How do you know if an object is an instance of a constructor function?

Answer 14

by using the instanceof keyword