javascript how to check if variable is a number code example

Example 1: if parameter is not number in js

let num1 = 'Hello';
if(isNaN(num1)){
    console.log(num1 + ' is not a number');
} else{
    console.log(num1 + ' is a number');
}

Example 2: check if something is a number

<html>
<head></head>
<body>
<h1>isNaN() example</h1>

<script type="text/javascript">
 var num1 = 100;
 if(isNaN(num1)){
    document.write(num1 + " is not a number <br/>");
 }else{
    document.write(num1 + " is a number <br/>");
 }
 
 var str1 = "mkyong"
 if(isNaN(str1)){
    document.write(str1 + " is not a number <br/>");
 }else{
    document.write(str1 + " is a number <br/>");
 }
</script>

</body>
</html>

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