Random Number Generator Javascript

In this tutorial, we will learn how to generate random numbers in javascript and we use a special method in javascript i.e.The Math.random() static method returns a floating-point, pseudo-random number that’s greater than or equal to 0 and less than 1, with approximately uniform distribution over that range — which you can then scale to your desired range. The implementation selects the initial seed to the random number generation algorithm; it cannot be chosen or reset by the user.

Math random() Syntax in JS

Math.random();

In Javascript random number simple syntax would be –

Math.random() Example in JavaScript

Example 1 :

const a = Math.random();

console.log(a);  // generating a random number

Output :

0.5856407221615856

Here, we have declared a variable a and assigned it a random number greater than or equal to 0 and less than 1.

Example 2 :

How to get a javascript Random Number between 1 and 10.

const a = Math.random() * (10-1) + 1
console.log(`Random value between 1 and 10 is ${a}`);  // generating a random number

Output :

A random value between 1 and 10 is 1.1488764328463117

Example 3 :

How to get a random value between the range of 1 to 10.

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

Output :

Random value between 1 and 10 is 5

For JavaScript random number, we used the Math.random() function. This method returns the value between 0 (inclusive) and 1 (exclusive).

This will show integer output between 1 (inclusive) to 10 (exclusive), i.e. (1 to 9). Here, Math.floor() is used to convert decimal to integer value.

Define a function to generate random numbers

From the above concept, we can create a function that takes two arguments, the highest and lowest to generate a random number between them and returns it.

Below is the code to define a function to return a random number from a given range :

function generateRandomNumber(lowest, highest) {    
let randomNumber = Math.random() * (highest - lowest) + lowest;
randomNumber = Math.floor(randomNumber); 
return randomNumber;
}

These functions can be called whenever there is a requirement of generating a random number, it is better to create a function instead of repeating the whole processor, again and again, to generate random numbers in different blocks.

Calling the above function :

const randomNumber = generateRandomNumber(1, 1000); 
console.log(randomNumber);

Output :

Similar to the Math.random() function, the Math.floor() function will generate a random number, but this function rounds down the number to the nearest whole number.

Syntax :

Math.floor(x);

Example :

function randomNumber(minimum, maximum) {
return Math.floor(Math.random() * (maximum - minimum) + minimum);
}
document.write("Generating a random number between the range 50 and 500: ")
// Here, we are calling the JavaScript function 
document.write('<strong>' + randomNumber(50, 500) + '</strong>');

Output :

Generating a random number between the range 50 and 500: 494

Math.random();

Example :

<html>
<head>
<title>Developer Helps | Javascript Random Number</title>
</head>
<body>
<h2>Javascript Random Number</h2>

Random Number between 0 and 1: <p id="random-number"></p>

<script>
document.getElementById("random-number").innerHTML = Math.random();
</script>

</body>
</html>

Output :

Javascript Random Number

Random Number between 0 and 1:
0.2535062639322767

JavaScript Random Integers

This example returns the random integer from 0 to 9.

Example :

<html>
<head>
<title>Developer Helps | Javascript Random Number</title>
</head>
<body>
<h2>Javascript Random Number</h2>

Random Integer between 0 and 9: <p id="random-number"></p>

<script>
document.getElementById("random-number").innerHTML = Math.floor(Math.random() * 10);
</script>

</body>
</html>

Output :

Javascript Random Number

Random Integer between 0 and 9:
2

JS Random Function

This JavaScript function returns a random number between min (included) and max (excluded).

Function :

function fetchRandomInteger(min, max) 
{
  return Math.floor(Math.random() * (max - min)) + min;
}

Example :

<html>
<head>
<title>Developer Helps | Javascript Random Number</title>
</head>
<body>
<h2>Javascript Random Number</h2>
<button onclick="fetchRandomInteger(0,10)">Try Click</button><br><br>
Random Function between min and max: <p id="random-number"></p>

<script>
function fetchRandomInteger(min, max) 
{
  document.getElementById("random-number").innerHTML = Math.floor(Math.random() * (max - min)) + min;
}
</script>

</body>
</html>

Output :

Javascript Random Number

Try Click

Random Function between min and max:
8

Thanks for the reading post. I hope you like and understand the post. If you have any doubts regarding this post please comment below.

Random Number Generator Javascript

Math random() Syntax in JS

Math.random() Example in JavaScript

Example 1 :

Output :

Example 2 :

Output :

Example 3 :

Output :

Define a function to generate random numbers

Output :

Syntax :

Example :

Output :

Example :

Output :

JavaScript Random Integers

Example :

Output :

JS Random Function

Function :

Example :

Output :

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