JavaScript: Arrays

Question 1

What is an array used for?
What is the syntax?

Answer 1

Arrays are used to store groups of data in a single variable.

const names = [“Andre”, “Karl”, “Rashida”, “Olivia”];

Question 2

How can an entire array can be accessed?
What is the syntax?

Answer 2

The entire array can be accessed by using the array’s name.

console.log(names);

Question 3

What does it mean that arrays are zero-indexed?

Answer 3

Arrays are zero-indexed, so the index of first element in the array is 0.

console.log(names[0]);

Question 4

How do you log a single element from an array?
What is the syntax?

Answer 4

const names = [“Andre”, “Karl”, “Rashida”, “Olivia”]
…
To log a single element, we use the name of the array with the index in brackets.

Returns “Karl” -
console.log(names[1]);

Question 5

How do you use index to replace data in an array?
What is the syntax?

Answer 5

const names = [“Andre”, “Karl”, “Rashida”, “Olivia”]
…
We can also use index to replace data in an array.

Returns “Olivia” -
console.log(names[3]);

Replaces “Olivia” with “Carter” -
names[3] = “Carter”;

Question 6

What is the syntax to log data from an array along with a phrase (string)?

Ex. The fourth name is [data-from-array].

Answer 6

const names = [“Andre”, “Karl”, “Rashida”, “Olivia”]
names[3] = “Carter”;
…

Logs “The fourth name is Carter.”

console.log(‘The fourth name is ${names[3]}.’);

Question 7

How can you determine the length of an array?
What is the syntax?

Answer 7

We use the array’s “length property” to determine how many elements are in the array.

arrayname.length

console.log(‘The length of the array is ${names.length}.`);