JavaScript Random Number

In this article, we will delve into the topic of generating random numbers in JavaScript. To begin with, it's essential to familiarize ourselves with the Math object.

What is a Math object?

JavaScript includes a predefined static object known as "Math".

This entity allows you to carry out mathematical computations. It is equipped with various pre-defined methods that facilitate the execution of mathematical tasks.

Syntax:

Math.method_name(number);

In JavaScript, we can generate a random number by utilizing the following methods:

• ✅ Math.random
• ✅ Math.floor

We will thoroughly understand these techniques through the use of demonstrations.

Math.random

This technique is employed to generate a random value ranging from 0 to 1, indicating that it consistently produces a number that is less than 1.

Syntax:

const num = Math.random();

Demonstrations:

We will examine the examples that illustrate how to create a random number using the Math.random function.

Demo 1:

We will generate a random decimal value ranging from 0 to 1 by employing the Math.random function.

Code:

const num = Math.random();
console.log(num);

Output:

In the output displayed below, we observe a decimal random number ranging from 0 to 1.

0.644745759039999

Demo 2:

In this demonstration, we will generate a random integer by employing Math.random.

Code:

const num = Math.random() * 2.5;
console.log(`${num} is a random whole number.`);

Output:

We can observe the result, which is a randomly generated integer.

2.1084120100254884 is a random whole number.

Demo 3:

We will generate a random number within a defined range by employing the Math.random function.

Code:

const getRandomNumber = (min, max) => {
  return Math.random() * (max - min) + min;
}

// Random number between 5 and 10
const random_num = getRandomNumber(5, 10);

console.log(random_num);

// Random number between 1 and 50
const random_num2 = getRandomNumber(1, 50);

console.log(random_num2);

Output:

The output demonstrates that random numbers are produced within defined intervals of 5 to 10 and 1 to 50.

7.560610340629418
18.87035185975946

Demo 4:

We will obtain a random integer value within a specified range by using the Math.random function.

Code:

const getRandomInteger = (min, max) => {
  min = Math.ceil(min);
  max = Math.floor(max);

  return Math.floor(Math.random() * (max - min)) + min;
}

// Random integer between 8 and 12
const randomInteger = getRandomInteger(8, 12);

console.log(randomInteger);

// Random integer between 15 and 75
const randomInteger2 = getRandomInteger(15, 75);

console.log(randomInteger2);

Output:

We can observe the result that comprises a random integer value falling within designated ranges.

Demo 5:

We will create a random number that includes the designated number of decimal places by employing the Math.random function.

Code:

function randomNumber (min, max, places) {
    const number1 = (Math.random() * (max - min + 1)) + min;
    return Number.parseFloat(number1).toFixed(places);
}

const number2 = randomNumber(4, 12, 2);
console.log(number2);

Output:

We can observe the result, which is a randomly generated number featuring two digits after the decimal point.

Math.floor

This function is utilized to truncate a number to the closest lower integer. It produces a random value that falls within the range of 0 to 1, indicating that the resulting number is consistently below 1. By combining Math.floor with Math.random, we can create a random integer.

Demo 1:

We will generate a random integer ranging from 0 to 10 without any decimal component by employing the Math.floor method.

Code:

const num = Math.floor(Math.random() * (10 - 1)) + 1;
console.log(`Random value between 0 and 10 is ${num}.`);

Output:

We can observe the result, which is a random integer ranging from 0 to 10, exclusive of any decimal points.

Random value between 0 and 10 is 4.

Demo 2:

We will generate a whole number that falls within the range specified by the two numbers provided by the users.

Code:

// input from the user
const min = parseInt(prompt("Enter a mininum value: "));
const max = parseInt(prompt("Enter a maximum value: "));

// getting a random number
const num = Math.floor(Math.random() * (max - min + 1)) + min;

// displaying a random number
console.log(`Random value between ${min} and ${max} is ${num}.`);

Output:

We can observe the output that displays a random integer without any decimal points, generated between the two numbers provided by the users.

Enter a mininum value: 60
Enter a maximum value: 105
Random value between 60 and 105 is 72.

Demo 4:

We will generate inclusive random numbers within a defined range by employing the Math.ceil, Math.floor, and Math.random functions.

Code:

const getRandomIntegerInclusive = (min, max) => {
  min = Math.ceil(min);
  max = Math.floor(max);

  return Math.floor(Math.random() * (max - min + 1)) + min;
}

// Random integer between 6 and 10, inclusive
const randomInteger1 = getRandomIntegerInclusive(6, 10);

console.log(randomInteger1);

// Random integer between 2 and 60, inclusive
const randomInteger2 = getRandomIntegerInclusive(2, 60);

console.log(randomInteger2);

Output:

We can observe the result, which is a random integer that falls between two specified numbers without any decimal points.

Conclusion:

In this article, we have explored the concept of generating random numbers in JavaScript. We have examined how to create a random number through various demonstrations. To achieve this, we can employ the Math.random and Math.floor functions.