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JavaScript Math random() method

The JavaScript Math.random() method returns the random number between 0 (inclusive) and 1 (exclusive).

In this article you will learn about “How to generate random number in JavaScript?”.

Syntax

Math.random()  

Parameters

Math.random() method does not require any parameters.

Return Value

The Math.random() method returns a random number from 0 (inclusive) up to but not including 1 (exclusive).

Example

Below is an example to find out the random number between 0 and 1.

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Example to find out random number between 0 and 1</title>
</head>

<body>
    <script>
        document.writeln(Math.random())
    </script>
</body>

</html>

Example 2

Below is a JavaScript function which always returns a random number between min and max (both included).

<!DOCTYPE html>
<html>

<body>

    <h2>JavaScript Math.random()</h2>

    <p>Every time you click the button, getRndInteger(min, max) returns a random number between 1 and 10 (both included):</p>

    <button onclick="document.getElementById('demo').innerHTML = getRndInteger(1,10)">Click Me</button>

    <p id="demo"></p>

    <script>
        function getRndInteger(min, max) {
            return Math.floor(Math.random() * (max - min + 1)) + min;
        }
    </script>

</body>

</html>

More examples

// Returns a random number:
Math.random();

// Returns a random integer from 0 to 9:
Math.floor(Math.random() * 10);

// Returns a random integer from 0 to 10:
Math.floor(Math.random() * 11);

// Returns a random integer from 0 to 99:
Math.floor(Math.random() * 100);

// Returns a random integer from 0 to 100:
Math.floor(Math.random() * 101);

// Returns a random integer from 1 to 10:
Math.floor(Math.random() * 10) + 1;

// Returns a random integer from 1 to 100:
Math.floor(Math.random() * 100) + 1;

//This JavaScript function always returns a random number between min (included) and max (excluded):
function getRndInteger(min, max) {
  return Math.floor(Math.random() * (max - min) ) + min;
}