Math.random()

Math.random() returns a floating-point number greater than or equal to 0, but strictly less than 1.

It utilizes an algorithm to generate these pseudo-numbers, but they are not truly random in a cryptographic sense. This means they can be predictable for certain applications.

Getting a random number between 1 and x

The way to do this is to multiply the Math.random() with the range to scale it. Range of numbers between max and min is (max - min + 1). So from 1 and 6 that would be $6-1+1=6$ . Remember 6 technically is excluded because in original 1 is excluded.

Edge cases When we get something close to 0 or something really close to max.

1. Close to zero : We add the min at the end to compensate for that
2. Close to max : We floor everything so max value is range value. So we add min to the result of random and then we floor the whole thing.

Between 1 and 6

range = 6, min = 1, max = 6 Large possible value = 5.99 + 1 = 6.99; floored down to 6

function getRandomNumberBetween(min, max) {
  // generates a random number between 0 (inclusive) and 1 (exclusive)
  const randomDecimal = Math.random();
 
  // Multiply random decimal by the range (max - min + 1) and floor the result
  // to get a random integer within the range.
  const randomNumber = Math.floor(randomDecimal * (max - min + 1) + min);
 
  return randomNumber;
}
 
// Get a random number between 1 and 6
const randomNum = getRandomNumberBetween(1, 6);
console.log(randomNum); // This will output a random number between 1 and 6
 

Between 2 and 10

range = 9, min = 2, max = 10 Large possible value = 8.99 + 2 = 10.99; floored down to 10 (max) Small possible value = 0.5 + 2 = 2.5; floored down to 2 (min)

Argument

Math.random() does not take any arguments