Globals

Question 1

Plus / Minus infinity

Answer 1

Number.POSITIVE_INFINITY;
Number.NEGATIVE_INFINITY;

Question 2

Assign NaN to a variable

Answer 2

a = Number.NaN;

Question 3

Check if integer is NaN

Answer 3

Number.isNaN() == isNaN(x);

Question 4

Check if variable is an integer number. Check if this integer is small enough to be processed by JS.

Answer 4

Number.isInteger();
Number.isSafeInteger();

Question 5

Small number (e.g. used for margin of error when comparing float)

Answer 5

Number.EPSILON;

Question 6

Pi value

Answer 6

Math.PI;

Question 7

Minimum, maximum value in array1

Answer 7

Math.min(...array1);
Math.max(...array1);

Question 8

• Round up
• Round down
• Round (regular rules)

Answer 8

Math.ceil(13.23); // 14
Math.floor(13.23); // 13
Math.round(13.23) // 13
// 13.53 will be 14

Question 9

Create current date object

Answer 9

const now = new Date();

Question 10

Create Date object of 15'th May 2023

Answer 10

new Date("2023-05-15");

new Date(2023, 4, 15)

Question 11

Change month to January in date object

Answer 11

now.setMonth(0);

Question 12

Basic date formatting options

Answer 12

now.toISOString(); // "2024-02-27T12:34:56.789Z" (UTC)
now.toDateString(); // "Tue Feb 27 2024"
now.toTimeString(); // "12:34:56 GMT+0000 (UTC)"
now.toLocaleDateString(); // Localized date
now.toLocaleTimeString(); // Localized time

Question 13

Get current date timestamp

Answer 13

Date.now();