JavaScript: isNaN() function
Description
The isNaN function is used to determine whether a value is "NaN" (not a number) or not. isNaN is a top-level function and is not associated with any object.
Syntax
isNan(testvalue)
Parameters
testvalue: The value to evaluate.
Example: isNaN() function
The following example shows how to use isNaN() function.
JavaScript Code:
console.log(isNaN("Good Morning"));
console.log(isNaN("2009/01/01"));
console.log(isNaN(455));
console.log(isNaN(-9.34));
console.log(isNaN(15-12));
console.log(isNaN(0));
View the example in the browser
Live demo:
See the Pen isnan-function-1 by w3resource (@w3resource) on CodePen.
Previous: JavaScript isFinite() function
Next: JavaScript: parseInt() function
Test your Programming skills with w3resource's quiz.
JavaScript: Tips of the Day
How to insert an item into an array at a specific index (JavaScript)?
What you want is the splice function on the native array object.
arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:
var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());
Ref: https://bit.ly/2BXbp04
- New Content published on w3resource:
- HTML-CSS Practical: Exercises, Practice, Solution
- Java Regular Expression: Exercises, Practice, Solution
- Scala Programming Exercises, Practice, Solution
- Python Itertools exercises
- Python Numpy exercises
- Python GeoPy Package exercises
- Python Pandas exercises
- Python nltk exercises
- Python BeautifulSoup exercises
- Form Template
- Composer - PHP Package Manager
- PHPUnit - PHP Testing
- Laravel - PHP Framework
- Angular - JavaScript Framework
- Vue - JavaScript Framework
- Jest - JavaScript Testing Framework