Javascript

Question 1

Code for

Exponent or Power

Answer 1

(**) or Math.pow(baseNumber, powerNumber)
Example: 2 ** 5 = 32

For squared exponent or power will always be 2
(6 ** 2), (20 ** 2), (3 ** 2)

Question 2

Find remainder

Answer 2

(%)
example: 11 % 2 = 1

finds the remainder
(Since 2 goes into 11, 5 times, the remainder is 1)
If using % 2 and remainder is 1, number is odd. If remainder is 0, number is even

Question 3

Sum (Plus-equals) (Increment)

Minus-equals (Decrement)

Product (Times-equals) (Multiplier)

Divide-equals (Divider)

Answer 3

Sum (+=)
Example: 11 += 2 = 13

Decrement (-=)
Example: 11 -= 2 = 9

Product (*=)
Example: 11 *= 2 = 22

Divider (/=)
Example: 12 /= 2 = 6

Question 4

Find Absolute Value

Answer 4

Math.abs()

Example: Math.abs(-295) = 295

Measures distance from 0
Answer will always be positive

Question 5

Round Up

Answer 5

Math.ceil()

Example: Math.ceil(33.7) = 34

Rounds up

Question 6

Round Down

Answer 6

Math.floor()

Example: Math.floor(33.7) = 33

Rounds down

Question 7

Code for

Parsing an integer from a string

Answer 7

Number.parseInt()

Question 8

Code for

Parsing a float from a string

Answer 8

Number.parseFloat()

Question 9

Generate a random Number

Answer 9

Math.random() * (max - min) + min)
(leave () blank)

Example: Math.random() * (10 - 1) + 1 =
Random number between 10 and 1

Question 10

Boolean Operator for

Not

Answer 10

(!)

Example: (!true = false), (!boolean = notBoolean)

Creates Opposite

Question 11

Boolean Operator for

Or

Answer 11

(||)

Example: (true || true = true), (true || false = true)
(false || false = false)

Both variables must be false to return false
All else is true

Question 12

Boolean Operator for

And

Answer 12

(&&)

Example: (false && false = false), (true && false = false)
(true && true = true)

Both variables must be true to return true
All else is false

Question 13

Boolean Operator for

Equal to

Answer 13

(===)

Example: (true === true = true), (false === false = true)
(true === false = false)

Both variables must be the same to return true
All else is false

Question 14

Boolean Operator for

Not equal to

Answer 14

(!==)

Example: (true !== false = true), (false !== true = true)
(true !== true = false)

Both variables must be different to return true
All else is false

Question 15

Find a Character in a string

Answer 15

“string”[index]

Example: “computer”[3] = p

Gets a specific character in a string
index always starts at 0

Question 16

Add together two or more strings without a space

Add together two or more strings with a space

Answer 16

(without a space)
“string1” + “string2”

Example: “comp” + “uter” = computer

(with a space)
“string1” + “ “ + “string2”

Example: “John” + “ “ + “Smith” = John Smith

Question 17

Interpolate a string

Answer 17

+ parameters +

Example:
“We will go “ + hiking + “ on “ + Tuesday + “.”
=
we will go hiking on Tuesday

Question 18

Get the length of a string

Answer 18

“string”.length

Example: “Apple”
“string”.length = 5

Tells you the length of the string

Question 19

Get the last character of a string

Answer 19

“string”[“string”.length - 1]

Example: “banana”
“string”[“string”.length - 1] = a

Tells you the last character in the string

Question 20

Get a portion of a string

Answer 20

“string”.substring(parameters)

Example: “Queue”
“string”.substring(1, 4) = ueu

Tells you a specific portion of a string
Starts at 0, ends before 2nd parameter

Question 21

Find the beginning index of a portion of a string

Answer 21

“string”.indexOf(substring)

Example: “Quicksort”
“string”.indexOf(“sort”) = 5

Tells you the index where a substring starts
Starts at 0

Question 22

Change not a string into a string

Answer 22

parameter.toString()
(fill in parameter), (leave () blank)

Example: 54.toString = “54”

converts parameter into single string

Question 23

Accessing an element in an Array

Answer 23

Array[index]

Example:
[water, coffee, tea][2]
array[index] = tea

Tells you the element at the given index
Index starts at 0

Question 24

Get the length of an Array

Answer 24

Array.length

Example:
[1, 3, 4, 5, 7]
array.length = 5

Tells you the number of elements in an array

Question 25

Remove the last element of an array

Answer 25

array.pop() (leave () blank) ``` Example: [1, 2, 3] array.pop() ; return array ; = [1, 2] ``` Tells you the last element in an array

Question 26

Add an element to the front of an array

Answer 26

array.unshift(newElement) ``` Example: [1, 2] array.unshift(3) ; return array ; = [3, 1, 2] ``` Adds new element to front of array

Question 27

Add an element to the back of an array

Answer 27

array.push(newElement) ``` Example: [1, 2] array.push(3) ; return array ; = [1, 2, 3] ``` Adds new element to back of array

Question 28

Remove an element from an array

Answer 28

array.splice(index where to delete, how many to delete) Example: [8, 9, 10, 10000, 11] array.splice(3, 1) = [8, 9, 10, 11] Removes indicated element Index starts at 0

Question 29

Add/remove an element to an array

Answer 29

array.splice (index add/delete, how many delete, newElements) Example: Add [8, 9, 10, 12].splice(3, 0, 11) = [8, 9, 10, 11, 12] Example: add and delete [8, 9, 10, 24, 17, 13] array.splice(3, 2, 11, 12) = [8, 9, 10, 11, 12, 13] Adds or Adds/Removes elements in an array Index starts at 0

Question 30

Determine if value is an array

Answer 30

Array.isArray(input) Example: Array.isArray([1, 2, 3]) = true Tells you whether or not the input is an array

Question 31

Copy an array or part of an array

Answer 31

array.slice(start index, end index) Example: copy part of an array ['q', 'u', 'e', 'u', 'e'].slice(1, 4) = ['u', 'e', 'u'] Example: copy entire array ['q', 'u', 'e', 'u', 'e'] array.slice() = ['q', 'u', 'e', 'u', 'e'] Leave () blank to copy entire array

Question 32

Add one array to another array

Answer 32

result.concat(array) ``` Example: var result = [] array of arrays[ ['a', 'b'], ['c', 'd'], ['e', 'f'] ] result = result.concat(array[i]) return result = ['a', 'b', 'c', 'd', 'e', 'f'] ``` Combines multiple arrays

Question 33

Turn an array into a string

Answer 33

array.join(element to replace comma in array) Example: ["my", "name", "is"] array.join(" ") = my name is Turns an array into a string

Question 34

Turn a string into an array

Answer 34

string.split(element to replace with a comma) Example: var name: "my name is" name.split(" ") = ["my", "name", "is"] Turns a string into an array

Question 35

Find the index of an element of an array

Answer 35

array.indexOf(element) Example: ["this", "is", "crazy"] array.indexOf("is") = 1 Tells you the index of the element Index starts at 0

Question 36

Access a value in an object

Answer 36

object[key] ``` Example: {who: "me", when: "now", what: "tea"} ["when"] obj[key] = "now" Tells you the property at the key in the object ```

Question 37

Remove a property (key: value) from an object

Answer 37

delete object[key] ``` Example: {who: "me", when: "now", what: "tea"} ["when"] delete obj[key] = {who: "me", what: "tea"} ``` Deletes both key and "property" at given key in object

Question 38

Average

Answer 38

Sum of numbers divided by amount of numbers Example: 12 + 27 + 5 + 9 = 53. 53/5 = 10.6 Average is 10.6

Question 39

Area of a Triangle

Answer 39

(Base x Height) / 2

Question 40

Number Cubed

Answer 40

Any number to the power of 3 Example: 3 ** 3 = 27

Question 41

Number Squared

Answer 41

Any number to the power of 2 Example: 3 ** 2 = 9

Question 42

Area of a Rectangle

Answer 42

Length * Width

Question 43

Perimeter of a Circle

Answer 43

2 * Math.PI * radius Math.PI is code for Pi

Question 44

Code for Pi

Answer 44

Math.PI

Question 45

Area of a Circle

Answer 45

Math.PI * radius ** 2 Pi times the Radius to the Power of 2 (or squared)

Question 46

Square Root

Answer 46

Math.sqrt(number)

Question 47

Remove from front of an array

Answer 47

array.shift() (leave () blank) ``` Example: [1, 2, 3] array.shift() ; return array ; = [2, 3] ```

Question 48

Strings have length properties. Numbers do not have length properties. Arrays do have a length property.

Answer 48

``` var string = "hello" string.length = 5 ``` ``` var number = 1 number.length = undefined ```

Question 49

.length includes spaces when measuring a string

Answer 49

``` var string = "what is up" string.length = 10 ```

Question 50

What is an object

Answer 50

An object is a datatype that helps us collect and organize many pieces of data. Inside is going to be Key: Value (Property)

Question 51

What is an Array

Answer 51

A piece of data that organizes many pieces of data. Can be anything from strings, to booleans, to numbers. Or even more nested arrays in an array. You can also have an object in an array.

Question 52

What is an Array

Answer 52

One piece of data that organizes many pieces of data. Can be anything from strings, to booleans, to numbers. Or even more nested arrays in an array. You can also have an object in an array.

Question 53

Property

Answer 53

key: value | A property can only have one key and one value

Question 54

Keys are strings

Answer 54

{ madeByAWizard: true } madeByAWizard is a string

Question 55

``` Dot Notation (shortcut) ```

Answer 55

``` Dot Notation will find the named key and output the value at named key. shortcut to bracket notation var magicObj = { secretCode: "open sesame" } magicObj.secretCode returns open sesame ```

Question 56

Bracket Notation | best to use

Answer 56

``` You can use bracket notation for any situation trying to get a value from an obj. var magicObj = { secretCode: "open sesame" } magicObj["secretCode"] returns open sesame ``` If putting a variable in Brackets you do not need ""

Question 57

Using a variable to represent a key | Bracket Notation

Answer 57

``` var magicObj = { familiars: ["frog", "bat", "cat", "owl"] } var animals = "familiars" magicObj[animals] returns ["frog", "bat", "cat", "owl"] ```

Question 58

console.log

Answer 58

kind of works as notes. You cant actually use it. Maybe your in your code and are wondering if the var howMuch is equal to 11, you can console.log. ``` var howMuch = 11 console.log(11 === howMuch) ``` it will return true of false console.log outside of function

Question 59

Return

Answer 59

Returns the result or something that can be used in your code return is always the last thing that your function does. Nothing else can happen after that

Question 60

Function

Answer 60

A set of instructions that we want the computer to execute

Question 61

typeof cannot tell the difference between an array and an object. How do you figure out if something is an array?

Answer 61

Which is why we must use Array.isArray to figue out if it is an array.

Question 62

Convert an Object into an Array

Answer 62

...

Question 63

Convert an Array into an Object

Answer 63

...

Question 64

You know something is a function because it has parenthesis ()

Answer 64

array. pop() | array. unshift()

Question 65

Type of

Answer 65

if (typeof(input) === "number") | if (typeof(input) === "string")

Question 66

Sumnation

Answer 66

Sumnation of the number 6 add all number below 6 1+2+3+4+5+6 = 21 ``` How to: n = 6 var sumnation = 0 -- iterate over the single number -- there is no length for (var i = 0; i <= n; i++) -- i needs to be <= to n because i is what we are adding -- add i to sumnation sumnation += i return sumnation; = 21 ```

Question 67

factorial

Answer 67

Factorial of the number 4 multiply all the numbers below 4 4*3*2*1 = 24 var must be 1 because of multiplication ``` How to: n = 4 var factorial = 1 -- iterate over single number for (var i = 1; i <= n; i++) -- i must be <= n -- multiply i by factorial factorial *= i return factorial; = 24 ```

Question 68

Compound Interest

Answer 68

``` // I = P(1 + (r/n)) ^ (n*t) - P // n is compoundingFrequency // t is timeInYears // r is interestRate ``` ``` Example: var compoundedInterest = (principal * Math.pow(1 + (interestRate/compoundingFrequency) , (compoundingFrequency * timeInYears))) - principal ``` return compoundedInterest; }

Question 69

Multiply between/ Sum between | starts at first number

Answer 69

(num1, num2) (2, 5) ``` var product = 1 for (var i = num1; i < num2; i++) product = product * i return product; = 24 ``` //starts at first number