Introduction to objects & Object methods

Question 1

What is an object?

Answer 1

An object is a collection of properties and a property is an association between a name (or key) and a value.

Example:
const person = {
  firstName: 'James'
  lastName: 'Bond'
};

Question 2

What is the difference between Objects and Arrays ?

Answer 2

The difference between objects and arrays is that in objects the order of the values does not matter when retrieving the values.

Question 3

How can properties be gotten from an object?

Answer 3

Properties can be gotten from an object using the Dot and the Bracket notation.

Example:-
DOT NOTATION
console.log(person.firstName);

BRACKET NOTATION
console.log(person[‘firstName’]);

Question 4

What is the difference between the Dot & Bracket Notation.

Answer 4

In the Dot notation only the real property name can be used and not a computed property name.

Example:-
USING BRACKET NOTATION
const nameKey = “Name”;
console.log(person.[‘first’ + nameKey]); // output : James.
Note: the above can’t be done using Dot Notation.

Question 5

How are new properties added to objects?

Answer 5

DOT NOTATION
person.job = ‘Spy’;

BRACKET NOTATION
person[‘car’] = ‘Aston Martin’;

Question 6

What is an Object method?

Answer 6

An object method is a function attached to an object.

Example:-

Question 7

What is an Object method?

Answer 7

An object method is a function attached to an object.

Example:-
const person = {
  firstName: 'James',
  lastName: 'Bond',
  calcAge: function(currentYear, birthYear){
    return currentYear - birthYear;
}
};