javascript check if a value is an int
// The Number.isInteger() checks to see if the passed value is an integer
// Returns true or false
Number.isInteger(2); //True
Number.isInteger(90); //True
Number.isInteger("37"); //False
Number.isInteger(false); //falsejavascript check if number
function isNumber(n) { return /^-?[\d.]+(?:e-?\d+)?$/.test(n); }
------------------------
isNumber('123'); // true
isNumber('123abc'); // false
isNumber(5); // true
isNumber('q345'); // false
isNumber(null); // false
isNumber(undefined); // false
isNumber(false); // false
isNumber(' '); // falsejavascript check if variable is number
function isNumber(n) {
return !isNaN(parseFloat(n)) && !isNaN(n - 0);
}check if a variable is a number in javascript
// as test cases we have two variables of which 1 is a number and the second one is a string
let x = 7;
let y = "hello"
let result1 = !Number.isNaN(x) // true
let result2 = !Number.isNaN(y) // flaseTo check if a value is a number in JavaScript
const value = 2
isNaN(value) //false
isNaN('test') //true
isNaN({}) //true
isNaN(1.2) //falsecheck 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>Copyright © 2021 Codeinu
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