Web Development Tutorial 10 Quiz Review

In Javascript, arrays sort in ​ (a)   order by default. The result of the following code:

var x = [3, 45, 1234, 24];

x.sort();

is ​ (b)  

• alphabetic
• 1234, 24, 3, 45
• ascending
• 3, 24, 45, 1234
• descending
• 1234, 45, 24, 3

Answer explanation

Increasing the value of the​ (a)   property adds more items to an array, but the items have (b)   values until they are defined.

• length
• null
• size
• array
• zero
• blank

Answer explanation

Changing the value of the length property changes the size of the array.

However, new values must be assigned to those array locations or they will be set to null. (Remember null is different than zero!)

By default, items are placed in an array either in the order in which they are defined or explicitly by index number.

• True

• False

Answer explanation

Javascript will assign variables in order (like when you specify a list of items at creation time) or by index (when you use assignment operators, like x[3] = "apple").

Identify a method that inserts new items at the front of an array.

• sort()

• unshift()

• reverse()

• assert()

Answer explanation

The ​ (a)   method extracts array items that match a specified condition.

• filter()
• sort()
• reverse()
• splice()

Answer explanation

What values does the variable i take as a result of the following code?

for(var i = 10; i > 0; i--)

• 9, 8, 7, 6, 5, 4, 3, 2, 1, 0

• 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

• 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

• 10, 9, 8, 7, 6, 5, 4, 3, 2, 1

Answer explanation

What is the result of x = 15 % 4?

• x = 3

• x = 4

• x = 3.75

• % is not a valid operator

Answer explanation

An array where each position matches the same position in another array is a ​ (a)   array.

• parallel
• literal
• recursive
• linear

Answer explanation

What is the output of the following code? (Scroll down to see all of the code.)

var prod = 1;

var x = [1, 3, 7, 11];

​

x.forEach(productArray);

​

function productArray(value)

{

    product *= value;

}

• 123

• 231

• 22

• 1

Answer explanation

For each loop through the array values, each number is multiplied by the new number.

So

1*1 = 1

1*3 = 3

3*7 = 21

12 * 11 = 231

Recall that *= is a short hand way of saying the left hand variable is multiplied by the right hand variable and then assigned back to itself.

In an array literal, the array values are a space-separated list within a set of curly brackets.

• True

• False

Answer explanation

Array literals are assigned to array values in a square brackets list:

x = ["fee", "fie", "foe", "fum"]