How to check if a variable is a number in javascript?

How to check if a variable is a number in javascript?

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()
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
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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AuthorAdmin

Greetings, I'm Devendra Dode, a full-stack developer, entrepreneur, and the proud owner of Tutsmake.com. My passion lies in crafting informative tutorials and offering valuable tips to assist fellow developers on their coding journey. Within my content, I cover a spectrum of technologies, including PHP, Python, JavaScript, jQuery, Laravel, Livewire, CodeIgniter, Node.js, Express.js, Vue.js, Angular.js, React.js, MySQL, MongoDB, REST APIs, Windows, XAMPP, Linux, Ubuntu, Amazon AWS, Composer, SEO, WordPress, SSL, and Bootstrap. Whether you're starting out or looking for advanced examples, I provide step-by-step guides and practical demonstrations to make your learning experience seamless. Let's explore the diverse realms of coding together.

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