Main deck

Question 1

What are “var, let, const”?

Answer 1

Declaration Keywords

Question 2

What does var do?

Answer 2

Declares a variable of global scope

Question 3

What does let do?

Answer 3

Declares a variable of block scope

Question 4

What does const do?

Answer 4

Declares a variable that cannot be reassigned.

Question 5

What does it mean to “declare a variable”?

Answer 5

It means telling the computer to open a slot in memory where it can place a value in the future.

Question 6

What can be stored in a variable?

Answer 6

Any “value” - numbers, strings, booleans, objects, etc.

Question 7

What are the 5 basic (or “primitive”) data types?

Answer 7

Number, string, boolean, undefined, null

Question 8

What’s the difference between ‘5’ and 5?

Answer 8

The first one is a string and the second one is a number.

Question 9

What does var x = 5 do?

Answer 9

Declares a variable called x and assigns the value 5 to it.

Question 10

Are semicolons required in javascript?

Answer 10

No but it’s a good idea to use them.

Question 11

What should the file extension be for a javascript file?

Answer 11

.js

Question 12

How do you get to a javascript console in terminal?

Answer 12

node

Question 13

What are the boolean values?

Answer 13

true and false

Question 14

What does (5+2) resolve to?

Answer 14

10

Question 15

What is the operator = called?

Answer 15

The assignment operator

Question 16

What does the operator = do?

Answer 16

Assigns the value on the right to the variable on the left.

Question 17

What are all these called: =, +, -, ==, %, !, !=

Answer 17

Operators

Question 18

What category of operators are all these: ==, &&;&&;, ||, !=

Answer 18

Boolean operators

Question 19

What is the operator == called?

Answer 19

The comparison operator

Question 20

What does the operator == do?

Answer 20

Compares both sides and returns true if they are equal (but not necessarily the same type).

Question 21

What is the operator === called?

Answer 21

“True equals” or “strict comparison” operator.

Question 22

What does the operator === do?

Answer 22

Compares both sides and returns true if they are equal (AND the same type!).

Question 23

What does the operator != do?

Answer 23

Returns true if the two sides are NOT equal.

Question 24

What is the operator ! called?

Answer 24

The negation operator (often called “NOT”).

Question 25

What does the operator `!` do?

Answer 25

Flips ("negates") the boolean value...true turns to false and false turns to true.

Question 26

What does `!!true && true` resolve to?

Answer 26

true

Question 27

What does `!(true || false) && !(true && false)` resolve to?

Answer 27

false

Question 28

How are parentheses used in programming?

Answer 28

Just like in math - they tell the computer to resolve everything inside the parentheses before doing anything else.

Question 29

Are you required to assign a value to a variable when you declare it?

Answer 29

No - you can write `var x` and that will declare the variable and the value will be undefined.

Question 30

What value does a variable have before you assign a value to it?

Answer 30

undefined

Question 31

What's the difference between var and let?

Answer 31

var gives you a variable with global scope and let gives you a variable with block scope

Question 32

What does it mean if a variable has global scope?

Answer 32

The variable can be used anywhere in the file.

Question 33

What does it mean if a variable has block scope?

Answer 33

The variable can only be used inside the block where it is declared.

Question 34

What is a "block"?

Answer 34

Code that is surrounded by { and } (curly braces)

Question 35

What is the operator `%` called?

Answer 35

Modulus

Question 36

What does the operator `%` do?

Answer 36

Computes the remainder of the number on the left when you divide it by the number on the right.

Question 37

What does the operator `>=` do?

Answer 37

Returns true if the number on the left is greater than or equal to the number on the right.

Question 38

What does `"5"+10` resolve to?

Answer 38

`510` (it converts the number 10 to string "10" before adding - this is called type coercion)

Question 39

What are two names for the following code: `if (...) {... }`

Answer 39

"If statement" and "conditional statement"

Question 40

What does syntax mean?

Answer 40

Syntax means the way something is written in code.

Question 41

What is the syntax for a conditional/if statement?

Answer 41

if (condition) { ... }

Question 42

What is the stuff inside the parentheses in an if statement called?

Answer 42

The condition

Question 43

What does an if statement do?

Answer 43

Tells the computer to only execute the code inside the block if the condition is true.

Question 44

``` What will be logged on the console for the following code? let x = 5; if (x == 5) { console.log('marko is a boss'); } else { console.log('raymond is a boss'); } ```

Answer 44

marko is a boss

Question 45

``` What will be logged on the console for the following code? let x = 5; if (x >= 6 || x <= 4) { console.log('marko is a boss'); } else { console.log('raymond is a boss'); } ```

Answer 45

raymond is a boss

Question 46

In a conditional statement, when is an "else if" block of code executed?

Answer 46

If the first condition was false but the condition after "else if" was true.

Question 47

In a conditional statement, when is an "else" block of code executed?

Answer 47

When the condition was false.

Question 48

What is the syntax of a for loop?

Answer 48

for (iterator declaration; iterator condition; iterator mutation) { .... }

Question 49

In a for loop, you always declare a variable right after the `for` keyword. What is that variable called in general?

Answer 49

The iterator

Question 50

What does it mean to "iterate" over an array?

Answer 50

To loop through the values of the array with a for loop.

Question 51

What is an object?

Answer 51

A collection of properties grouped together in one variable name.

Question 52

What is the syntax to declare a variable and assign an empty object to it?

Answer 52

let myObject = {};

Question 53

What is the syntax for accessing a property called "color" in an object called "paint"?

Answer 53

paint.color or paint['color'] (notice the quotes in the second one)

Question 54

Suppose you declare an object `let x = {color:'green', size:10};`. What are "color" and "size" called?

Answer 54

Keys or properties

Question 55

Suppose you declare an object `let x = {color:'green', size:10};`. What are "color" and "size" called?

Answer 55

Values

Question 56

What is an array?

Answer 56

A list of values grouped together in one variable name.

Question 57

Suppose you declare an array `let myArray = [1,2,3]`. What does `myArray[1]` resolve to?

Answer 57

2 (because the index starts at zero)

Question 58

Suppose you have an array called myArray. In the code `myArray[6]`, what is the stuff inside the square brackets called?

Answer 58

The index

Question 59

When you have a variable or object called myObject, using the `.` (dot) operator allows you to...

Answer 59

access any of the object's properties or methods.

Question 60

What is a method?

Answer 60

A function attached to an object or variable.

Question 61

What is a function?

Answer 61

A block of code that you can reuse by replacing the arguments with any value you want.

Question 62

Does a function have to have arguments?

Answer 62

No

Question 63

Does a function have to return something?

Answer 63

No

Question 64

If a function accepts something as input, the input(s) are called...

Answer 64

argument(s)

Question 65

How does a method differ from a function?

Answer 65

A method is just a function that is attached to a variable, so it does something with the variable it is attached to.