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JavaScript Random

Math.random()

Math.random() is used to return a random number between 0 (inclusive),  and 1 (exclusive):

Example

<!DOCTYPE html>

<html>

<body>

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

<p>Math.random() returns a random number between 0 (included) and 1 (excluded):</p>

<p id=”demo”></p>

<script>

document.getElementById(“demo”).innerHTML = Math.random();

</script>

</body>

</html>

Output

JavaScript Math.random()

Math.random() returns a random number between 0 (included) and 1 (excluded):

JavaScript Random Integers

Math.random() used with Math.floor() returns random integers.

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Math</h2>

<p>Math.floor(Math.random() * 10) returns a random integer between 0 and 9 (both

included):</p>

<p id=”demo”></p>

<script>

document.getElementById(“demo”).innerHTML =

Math.floor(Math.random() * 10);

</script>

</body>

</html>

Output

JavaScript Math

Math.floor(Math.random() * 10) returns a random integer between 0 and 9 (both included):

Another Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript Math</h2>

<p>Math.floor(Math.random() * 100)) returns a random integer between 0 and 99

(both included):</p>

<p id=”demo”></p>

<script>

document.getElementById(“demo”).innerHTML =

Math.floor(Math.random() * 100);

</script>

</body>

</html>

Output

JavaScript Math

Math.floor(Math.random() * 100)) returns a random integer between 0 and 99 (both included):

This JavaScript function returns a random number between min and max (both included):

Example

<!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>

Output

JavaScript Math.random()

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