Chapter 1: Values, Types, and Operators

Question 1

JavaScript expression for the remainder of 10 divided by 3

Answer 1

10 % 3

Question 2

Three special numbers in JS

Answer 2

Infinity
-Infinity
NaN

Question 3

Three ways to write a string in JS

Answer 3

“Double quotes”
‘Single quotes’
Backticks

Question 4

Escape character in JS

Answer 4

Backslash

Question 5

String concatenation

Answer 5

+

Question 6

What is a “template literal”?

Answer 6

A string which can embed a calculated or object value

Question 7

How do you write a template literal?

Answer 7

Use backticks around text, with values to be computed surrounded by ${}

Question 8

How to return to type of a value

Answer 8

With the “typeof” operator: typeof “string” -> string

Question 9

JS “and” operator

Answer 9

&&

Question 10

JS “or” operator

Answer 10

||

Question 11

JS conditional operator (and example)

Answer 11

? :

false ? 7 : 3 -> 3

Question 12

What is “type coercion?

Answer 12

When JS is told to use an operator on values of differing types, it will try to force on value to be the type of the other

Question 13

How can you avoid false from getting automatically converted to 0 or “” in a comparison to a number or string?

Answer 13

Use === instead of == or !== instead of !=

Question 14

What is “short-circuit evaluation”?

Answer 14

A behavior in JS in which the only value in an expression that is evaluated is the value that is selected; non-selected values are not evaluated

Question 15

Give an example of short-circuit evaluation

Answer 15

true || “not selected” -> true

Question 16

How do && and || work on string and number values?

Answer 16

0, NaN, and “” count as false and all other strings and numbers count as true. If the number or string being evaluated as true or false is chosen by the operator, that same value is returned by the expression.