### JavaScript generate Random number example

To generate a random number in JavaScript you have to use the Math.random() function. The JavaScript function Math.random() randomly generates a number from 0 to slightly less than 1.But our objective is to say generate a random number between 0 and 9999. So how do we achieve that? What we do is take the result of Math.random() and multiply that by 10000 which will result in something between 0 and slightly less than 10000 and then we use another function called Math.floor() to make that an integer. Math.floor() returns the largest integer less than or equal to a number.

#### Here is how to generate a random number between 0 and 9999

```var randomValue = Math.floor(Math.random() * 10000);
```

#### Sample program with some useful random functions

```<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Generate a Random Number using Javascript</title>
<style type="text/css">
body {
margin: 10px 10px 10px 10px;
}
</style>
<script type="text/javascript" src="extjs/ext-all-debug.js"></script>
<script type="text/javascript" src="random.js"></script>
<body>

</body>
</html>
```

#### Source for JavaScript file - random.js

```Ext.Loader.setConfig({
enabled: true
});

Ext.application({

name: 'MyApp',
appFolder: 'app',

launch: function() {

//max 2 digit random number - between 0 and 99
console.log(this.getRandom(2));
//max 5 digit random number - between 0 and 99999
console.log(this.getRandom(5));
//get random number between 100 and 999
console.log(this.getRandomMinMax(100,999));

},

getRandom :  function(size) {
return Math.floor(Math.random() * (Math.pow(10,size)));
},

getRandomMinMax :  function(min, max) {
return Math.floor(Math.random() * (max - min + 1)) + min;
}

});
```