Quiz Questions

Question 1

When was Typescript Introduced and by whom?

Answer 1

October 2012 by Microsoft

Question 2

How can you compile Typescript into Javascript

Answer 2

change directory (cd folder)
npx tsc –watch

Question 3

What is the purpose of variables?

Answer 3

Storing data in a name to be reused.

Question 4

How do you declare a variable?

Answer 4

Using keywords const or let.

Question 5

How do you initialize a variable?

Answer 5

Using the assignment operator (=)

Question 6

What characters are allowed in variable names?

Answer 6

letters, numbers, $, _

Question 7

What does it mean to say that variable names are “case sensitive”?

Answer 7

two variables with the same text but different capitalization are different variables and don’t necessarily hold the same value.

Question 8

What is the purpose of a string?

Answer 8

Holding text data.

Question 9

What is the purpose of a number?

Answer 9

Holding integer and floating point data.

Question 10

What is the purpose of a boolean?

Answer 10

To hold true or false data

Question 11

What does the = operator mean in JavaScript?

Answer 11

It is the assignment operator and is used to assign value to a variable.

Question 12

How do you update the value of a variable?

Answer 12

If the variable is declared with the keyword ‘let’, you can reassign the value of that variable using the assignment operator or an incremental operator like “+=” or “-+”.

Question 13

What is the difference between null and undefined?

Answer 13

Null is a value that is purposefully not provided. Undefined has an undeclared value

Question 14

Why is it a good habit to include “labels” when you log values to the browser console?

Answer 14

To help clarify what the log is noting.

Question 15

Give five examples of JavaScript primitives.

Answer 15

number
string
boolean
null
undefined

Question 16

What data type is returned by an arithmetic operation?

Answer 16

Number

Question 17

What is string concatenation?

Answer 17

Adds a string and another data type into a string.

Question 18

What purpose(s) does the + plus operator serve in JavaScript?

Answer 18

Adds numeric values together, string concatenation, and reassigning variables of other types into number.

Question 19

What data type is returned by comparing two values (<, >, ===, etc)?

Answer 19

Boolean

Question 20

What does the += “plus-equals” operator do?

Answer 20

Adds the value in the variable with whatever is behind the operator, and then reassigns it to the same variable.

Question 21

What is the syntax for writing a template literal?

Answer 21

backtick with string and any ${string interpolation} within

Question 22

What is “string interpolation”?

Answer 22

The ability to add variable values into a string

Question 23

What are objects used for?

Answer 23

Objects are used to hold various data and their pairs.

Question 24

What are object properties?

Answer 24

The “key:value” pair that are housed within an object.

Question 25

Describe object literal notation.

Answer 25

Various key:value pairs are separated by commas between curly braces and assigned to a variable.

Question 26

How do you remove a property from an object?

Answer 26

delete variableName["keyName"]

Question 27

What are the two ways to get or update the value of a property?

Answer 27

dot notation and bracket notation

Question 28

What is the purpose of interfaces in TypeScript?

Answer 28

Assigning data typing to the values of each property, so that data is not mismanaged upon creation.

Question 29

How do optional properties in a TypeScript interface differ from mandatory properties, and why are they useful?

Answer 29

They are not required to create an object in all cases, but may be utilized later in the code.

Question 30

What are arrays used for?

Answer 30

storing like data in a indexed way.

Question 31

Describe array literal notation.

Answer 31

values within [ ]

Question 32

How are arrays different from "plain" objects?

Answer 32

Indexed

Question 33

What number represents the first index of an array?

Answer 33

0

Question 34

What is the `length` property of an array?

Answer 34

tells how many items are within an array.

Question 35

How do you calculate the last index of an array?

Answer 35

arrayName.length - 1

Question 36

What is a function in JavaScript?

Answer 36

a way to systematically package code to be easily reused later in the code.

Question 37

Describe the parts of a function **definition**.

Answer 37

functionKeyword functionName (parameters) { code block; return optional; }

Question 38

Describe the parts of a function **call**.

Answer 38

functionName(arguments);

Question 39

When comparing them side-by-side, what are the differences between a function **call** and a function **definition**?

Answer 39

The block of code and the functionality is created and done within the definition, then simply utilized in the call through the function name.

Question 40

What is the difference between a **parameter** and an **argument**?

Answer 40

parameter is the template placeholder in the definition of a function, the argument is what is passed through when the function is called.

Question 41

Why are function **parameters** useful?

Answer 41

Since we won't know the actual values of what we are passing in, the placeholders are useful.

Question 42

What two effects does a `return` statement have on the behavior of a function?

Answer 42

Breaks the function so that any code under it is unreachable. It also passes a value from the function.

Question 43

What is the syntax for defining an arrow function?

Answer 43

const variable = (parameters) => { codeblock };

Question 44

When an arrow function's body is not surrounded in curly braces (concise body syntax), what changes in its functionality?

Answer 44

There is an automatic return value if it is in one line.

Question 45

What is a method?

Answer 45

a function that exists as a property of an object.

Question 46

How is a method different from any other function?

Answer 46

it is specific to the object it exists within.

Question 47

How do you remove the last element from an array?

Answer 47

array.pop()

Question 48

How do you round a number down to the nearest integer?

Answer 48

Math.floor(number)

Question 49

How do you generate a random number?

Answer 49

Math.random()

Question 50

How do you delete an element from an array?

Answer 50

array.splice(start, length)

Question 51

How do you append an element to an array?

Answer 51

array.push()

Question 52

How do you break a string up into an array?

Answer 52

array.split("character at which to split")

Question 53

Do string methods change the original string?

Answer 53

No

Question 54

How do you get a collection of an objects keys?

Answer 54

Object.keys(objectName)

Question 55

How do you get a collection of an objects values?

Answer 55

Object.values(objectName)

Question 56

How do you get a collection of both an objects keys and values?

Answer 56

Object.entries(objectName)

Question 57

Give 6 examples of comparison operators.

Answer 57

===, <, >, <=, >=, !==

Question 58

What is the purpose of an `if` statement?

Answer 58

to process a block of code only if a condition is met.

Question 59

Describe the syntax (structure) of an `if` statement.

Answer 59

ifKeyword (conditional statement) {code}

Question 60

What are the three logical operators?

Answer 60

&&, ||, !

Question 61

How do you compare two different expressions in the same condition?

Answer 61

AND && or OR ||

Question 62

What is the purpose of a `switch` statement?

Answer 62

to have different actions take place depending on the value of an input.

Question 63

What is the purpose of a loop?

Answer 63

To be able to repeat code multiple times on the same or different data.

Question 64

What is the purpose of a **condition** expression in a loop?

Answer 64

To only run the code while a condition is being met.

Question 65

What does "iteration" mean in the context of loops?

Answer 65

It references each time a loop is cycled and code is run.

Question 66

_When_ does the **condition** expression of a `while` loop get evaluated?

Answer 66

Before each time the code is run.

Question 67

_When_ does the **initialization** expression of a `for` loop get evaluated?

Answer 67

Before the first iteration of the loop.

Question 68

- _When_ does the **condition** expression of a `for` loop get evaluated?

Answer 68

Before each iteration of the loop.

Question 69

_When_ does the **final** expression of a `for` loop get evaluated?

Answer 69

After each iteration of the loop.

Question 70

Besides a `return` statement, which exits its entire function block, which keyword exits a loop before its **condition** expression evaluates to `false`?

Answer 70

break;

Question 71

What does the `++` increment operator do?

Answer 71

adds 1 to a value and reassigns it to itself.

Question 72

How do you iterate through the keys of an object?

Answer 72

a for in loop.