To generate a random number using JavaScript, the simplest way is to use the JavaScript **random()** method:

`var random = Math.random();`

Random number generation with JavaScript is easy to do. All we need is the Javascript Math **random()** method.

The Javascript Math **random()** method generates a number between 0 and 1 (including 0 and excluding 1).

Let’s say we want to generate 10 random numbers between 0 and 1. We can loop 10 times, calling the Math **random()** method inside the loop, and create an array with these 10 random numbers. Since the numbers returned will be decimals between 0 and 1, to make things more practical, we can multiply the result by 10 and then use the Math.round() method to get an integer value between 0 and 10. We can also multiply by 100 to get a number between 0 and 100, which is what we will do.

```
var randoms = [];
for (var i = 0; i < 10; i++) {
randoms.push(Math.round((Math.random()*100)))
}
console.log(randoms);
```

A possible output (because it’s random) for generating 10 random numbers using the code above could be:

`[100, 50, 11, 2, 32, 53, 84, 71, 65, 24]`

## Generating a Random Number on Click Using JavaScript

To generate a random number on click using JavaScript, we can combine the Math **random()** method with a click event.

Let’s say we have the following HTML, and we want to give the user the ability to generate a random number and show the random number in a span.

```
<div id="div1">
<div id="click-me" onclick="genRandomNum()">Generate random number</div>
<p>Our generated random number is: <span id="rand"></span></p>
</div>
```

We can utilize the **onclick** event, Math **random()** method, the Math **round()** method, and the **innerHTML** property to change the text of the span.

Below is the JavaScript code which will allow the user to be able to update the text in the paragraph with a random number. We will do as we did above and multiply the number by 100 and round it to get and integer from 0 to 100.

```
function genRandomNum(){
document.getElementById("rand").innerHTML = (Math.round((Math.random()*100)));
}
```

The final code and output for this example of how to generate a random number on click using Javascript is below:

Code Output:

Our generated random number is:

Full Code:

```
<div id="div1">
<div id="click-me" onclick="genRandomNum()">Generate random number</div>
<p>Our generated random number is: <span id="rand"></span></p>
</div>
<script>
function genRandomNum(){
document.getElementById("rand").innerHTML = (Math.round((Math.random()*100)));
}
</script>
```

Hopefully this article has been useful for you to understand how to generate a random number using Javascript.

## Leave a Reply