To check if a variable is not a number in javascript; In this tutorial, You will learn how to check whether a variable or given value is number or not in javascript
This tutorial will provide a test demo to checking a given value or variable is number or not. So try these examples use it.
javaScript check if variable is a number
- isNaN() JavaScript – isNaN Stands for “is Not a Number”, if a variable or given value is not a number, it returns true, otherwise it will return false.
- typeof JavaScript – If a variable or given value is a number, it will return a string named “number”. In JavaScript, the typeof operator returns the data type of its operand in the form of a string.
1. isNaN JavaScript
Let’s take a new example of JavaScript’s “isNaN” method.
<!DOCTYPE html>
<html>
<title>Check if variable is a number or not in JavaScript Using isNaN()</title>
<head></head>
<body>
<h1>Check if variable is a number or not in JavaScript Using isNaN()</h1>
<input type="text" id="demo" value="" placeholder="Please enter here.....">
<button onclick="myFunction()">Click & See Result</button>
<script type="text/javascript">
function myFunction() {
var num = document.getElementById("demo").value;
console.log(num);
if(isNaN(num)){
alert(num + " is not a number");
}else{
alert(num + " is a number");
}
}
</script>
</body>
</html>
Demo
Check if variable or given value is a number or not in JavaScript Using isNaN()
2. typeof JavaScript
Let’s take a new example of JavaScript’s “typeof” operator.
<!DOCTYPE html>
<html>
<title>Check if variable or given value is a number or not in JavaScript Using javascript Typeof</title>
<head></head>
<body>
<h1>Check if variable or given value is a number or not in JavaScript Using javascript Typeof</h1>
<input type="text" id="demo1" value="" placeholder="Please enter here.....">
<button onclick="javascriptTypeof()">Click & See Result</button>
<script type="text/javascript">
function javascriptTypeof() {
var num = document.getElementById("demo1").value;
if(typeof num == 'number'){
alert(num + " is a number");
}else{
alert(num + " is not a number");
}
}
</script>
</body>
</html>
Demo
Check if variable or given value is a number or not in JavaScript Using javascript Typeof Operator
Conclusion
To check if a variable is not a number in javascript; In this tutorial, you have learned easy two ways to check a given value is number or not with example and live demos.
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