check if type is number javascript code example

Example 1: javascript check if number

//Updated dec 2020
// The first 2 Variations return a Boolean
// They just work the opposite way around

// IsInteger
if (Number.isInteger(val)) {
	// It is indeed a number
}

// isNaN (is not a number)
if (isNaN(val)) {
	// It is not a number
}

// Another option is typeof which return a string
if (typeof(val) === 'number') {
	// Guess what, it's a bloody number!
}

Example 2: javascript check if number

// The first 2 Variations return a Boolean
// They just work the opposite way around

// IsInteger
if (Number.isInteger(val)) {
	// It is indeed a number
}

// isNaN (is not a number)
if (isNaN(val)) {
	// It is not a number
}

// Another option is typeof which return a string
if (typeof(val) === 'number') {
	// Guess what, it's a bloody number!
}

Example 3: javascript check if variable is number

function isNumber(n) {
  return !isNaN(parseFloat(n)) && !isNaN(n - 0);
}

Example 4: 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 5: To check if a value is a number in JavaScript

const value = 2
isNaN(value) //false
isNaN('test') //true
isNaN({}) //true
isNaN(1.2) //false

Example 6: 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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