Numbers 16

Question 1

What are the two kinds of numeric values is JS?

Answer 1

Numbers: 64-bit floating point numbers and are also used for smaller integers
Bigints: represent numbers w an arbitrary precision

Question 2

Whats the difference between ++/– as a prefix rather than a suffix?
foo++ vs. ++foo

Answer 2

prefix: it adds to foo then returns foo
suffix: it returns foo then adds to it

Question 3

What are the three ways of converting values into numbers?

Answer 3

Number(x)
+x
parseFloat(x) (avoid this one)

Question 4

What is the rule for finding NaN in arrays?

Answer 4

There is no rule. You must check to see how each array method handles NaN.

Question 5

Why should you be careful with decimal fractions in JS?

Answer 5

Internally, js floating point numbers are represented with base 2, which means base 10 decimal fractions can’t always be represented precisely.

Question 6

What are the four ways of converting Numbers to Integers in js?

Answer 6

Math.trunc chops off anything past deci
Math.floor always rounds down
Math.ceil always rounds up
Math.round rounds up or down