JavaScript Cookbook, 3rd Edition

Chapter 3. Numbers

There are few ingredients more essential to everyday programming than numbers. Many modern languages have a set of different numeric data types to use in different scenarios, like integers, decimals, floating point values, and so on. But when it comes to numbers, JavaScript reveals its rushed, slightly improvised creation as a loosely-typed scripting language.

Until recently, JavaScript had just a single do-everything numeric data type called Number. Today, it has two: the standard Number you use almost all of the time, and the very specialized BigInt that you only consider when you need to deal with huge whole numbers. You’ll use both in this chapter, along with the utility methods of the Math object.

Generating Random Numbers

Problem

You want to generate a random whole number that falls in a set range (for example, from 1 to 6).

Solution

You can use the Math.random() method to generate a floating-point value between 0 and 1. Usually, you’ll scale this fractional value and round it, so you end up with an integer in a specific range. Assuming your range spans from some minimum number min to a maximum number max, here’s the statement you need:

randomNumber = Math.floor(Math.random() * (max - min + 1) ) + min;

For example, if you want to pick a random number between 1 and 6, the code becomes:

const randomNumber = Math.floor(Math.random()*6) + 1;

Now possible values of randomNumber are 1, 2, 3, 4, 5, or 6.

Discussion

The Math object is stocked full of static ...