Head First

Question 1

JS Functions: Pass by value or reference

Answer 1

Pass by value

Question 2

You can find the length of an array using

Answer 2

array.length

Question 3

Function to generat e uniform random values

Answer 3

Math.random

Question 4

Function to round to the previous integer

Answer 4

Math.floor

Question 5

The ____ function can used to trigger a print event from the browser

Answer 5

print

Question 6

To write to the console, you use

Answer 6

console.log

Question 7

How can you delete a property of an object?

Answer 7

By using the delete keyword

Question 8

Variables can only contain _____ to objects

Answer 8

References

Question 9

Pass by value applies for objects. But, changing the property of an object in a function changes the property in the original object. Is this true?

Answer 9

Yep

Question 10

How do you iterate over the properties of an object?

Answer 10

for (var prop in object) { do stuff };

Question 11

If two objects have different types, then try to convert them to a single type and compare. The ___ operator does this

Answer 11

==

Question 12

The condition is true iff the two objects have the same type and value. The __ operator does this

Answer 12

===

Question 13

The following are falsey by default

Answer 13

undefined, null, NaN, ‘’, 0

Question 14

___ property gives the length of the string

Answer 14

length

Question 15

The ___ method can be used to index a string

Answer 15

charAt

Question 16

The ___ method takes a string as an argument and returns the index of the first character of the first occurrence of that argument in the string

Answer 16

indexOf

Question 17

Give the ____ method two indices, and it will extract and return the string contained within them

Answer 17

substring

Question 18

The ___ method takes a character that acts as a delimiter, and breaks the string into
parts based on the delimite

Answer 18

split

Question 19

The ___ method returns a string with all uppercase characters changed to lowercase

Answer 19

toLowerCase

Question 20

The ___ method finds substrings and replaces them with another string.

Answer 20

replace

Question 21

The ___ method returns a new string that has part of the original string removed.

Answer 21

slice

Question 22

The ___ method is like indexOf, but finds the last, not the first, occurrence.

Answer 22

lastIndexOf`

Question 23

The ___ method joins strings together

Answer 23

concat

Question 24

The ____ method searches for matches in a

string using regular expressions

Answer 24

match

Question 25

The ____ method returns a string with all lowercase characters changed to uppercase.

Answer 25

toUpperCase

Question 26

The ____ method removes whitespace from around the string. Handy when processing user input.

Answer 26

trim

Question 27

When you want to handle time based events, you call the ____ function and pass it two things. What are those?

Answer 27

setTimeout, event handler function and time period in milliseconds

Question 28

Get this event
when you click (or
tap) in a web page

Answer 28

click

Question 29

The event you get when the browser has completed loading a web page.

Answer 29

load

Question 30

When you move your
mouse over an element,
you’ll generate this event

Answer 30

mousemove

Question 31

This event is generated

every time you press a key

Answer 31

keypress

Question 32

This event is generated
when you close the browser
window, or navigate away
from a web page

Answer 32

unload

Question 33

When you put
your mouse over
an element, you’ll
generate this event

Answer 33

mouseover

Question 34

And you’ll generate this
event when you move your
mouse off an element.

Answer 34

mouseout

Question 35

Whenever you resize
your browser window,
this event is generated.

Answer 35

resize

Question 36

Got in your page?

You’ll get these events when you click the play and pause buttons respectively.

Answer 36

play and pause

Question 37

If you drag an element
in the page, you’ll
generate this event.

Answer 37

dragstart

Question 38

On touch devices, you’ll
generate these
events when you touch and
hold an element and stop touching respectively

Answer 38

touchstart and touchend

Question 39

You’ll get this event when
you drop an element
you’ve been dragging

Answer 39

drop

Question 40

The _____ constructor is used to create objects

Answer 40

Object

Question 41

The _____ constructor is used to construct Math objects

Answer 41

Math

Question 42

Use this constructor to create regular expression objects, which allow you to search for patterns, even complex ones, in text.

Answer 42

Regexp

Question 43

This constructor creates standard error objects that are handy when catching errors in your code.

Answer 43

Error

Question 44

You can use the __________ method that every object has. The _______ method returns true if a property is defined in an object instance.

Answer 44

hasOwnProperty

Question 45

Every prototype chain you create in JavaScript will end in _______

Answer 45

Object

Question 46

The following properties of Object should not be overridden in any object which inherits from Object

Answer 46

constructor, hasOwnProperty, isPrototypeOf, propertyIsEnumerable