# How to check whether a number is finite or not in JavaScript?

In this article, we are going to discuss how to check whether a number is finite or not with suitable examples in JavaScript.

To check whether a number is finite or not in JavaScript, there is an inbuilt method which is isFinite() method. This method returns true if the number is a finte number. If the number is not a dfinite number, this method returns false.

To get a better understanding let’s look into the syntax and usage of isFinite() method in JavaScript.

## Syntax

The syntax to check whether a number is finite or not is −

isFinite(value)


Where, value is the value that is to be checked whether it is finite or not. It can be any primitive data type. The return value is either true or false.

### Example 1

This is an example program to write a function that checks a number whether it is finite or not.

<html>
<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>To check whether a number is finite or not in JavaScript?</title>
<body style="text-align: center;">
<p>To check whether a number is finite or not in JavaScript</p>
<p>Whether a function returns a finite number or not</p>
<p id="result"></p>
<script>
function Division(a){
if(isFinite(1/a)){
return "1/"+a+" is a finite number";
}
else{
return "1/"+a+" is not a finite number";
}
}
document.getElementById('result').innerHTML = Division(770)+'<br/>'+Division(0);
</script>
</body>
</html>


The output for the above example program is −

### Example 2

This is an example program for which isFinite() method returns only true.

<html>
<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>To check whether a number is finite or not in JavaScript?</title>
<body style="text-align: center;">
<p>To check whether a number is finite or not in JavaScript</p>
<p>In this program, we will discuss the examples where the isFinite() method returns true.</p>
<p id="result"></p>
<script>
var a = isFinite(12);
var b = isFinite(-12);
var c = isFinite(0);
var d = isFinite(1.2);
var e = isFinite(2000*3000);
document.getElementById('result').innerHTML = 'isFinite(12) : '+a+'<br/>'+ 'isFinite(-12) : '+b+'<br/>'+'isFinite(0) : '+c+'<br/>'+ 'isFinite(1.2) : '+d+'<br/>'+'isFinite(2000*3000) : '+e+'<br/>';
</script>
</body>
</html>


On executing the above code, the below output is generated.

### Example 3

This is an example program for which the isFinite() method returns only false.

<html>
<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>To check whether a number is finite or not in JavaScript?</title>
<body style="text-align: center;">
<p>To check whether a number is finite or not in JavaScript</p>
<p>In this program, we will discuss the examples where the isFinite() method returns false.</p>
<p id="result"></p>
<script>
var a = isFinite(NaN);
var b = isFinite("hello");
var c = isFinite(22 / 0);
var d = isFinite("01/01/2001");
document.getElementById('result').innerHTML = 'isFinite(NaN) : ' + a + '<br/>' + 'isFinite("hello") : ' + b + '<br/>' + 'isFinite(22/0) : ' + c + '<br/>' + 'isFinite("01/01/01") : ' + d;
</script>
</body>
</html>


On executing the above code, the below output is generated.