JavaScript isNaN() Function Last Updated : 30 Nov, 2022 Comments Improve Suggest changes Like Article Like Report The JavaScript isNaN() Function is used to check whether a given value is an illegal number or not. It returns true if the value is a NaN else returns false. It is different from the Number.isNaN() Method. Syntax: isNaN( value ) Parameter Values: This method accepts a single parameter as mentioned above and described below: value: It is a required value passed in the isNaN() function. Return Value: It returns a Boolean value i.e. returns true if the value is NaN else returns false. Example: In this example, we will check various values for isNan() and the output will be in boolean format. JavaScript <script> console.log(isNaN(12)); console.log(isNaN(0 / 0)); console.log(isNaN(12.3)); console.log(isNaN("Geeks")); console.log(isNaN("13/12/2020")); console.log(isNaN(-46)); console.log(isNaN(NaN)); </script> Output: false true false true true false true We have a complete list of Javascript Function methods, to check those please go through this Javascript Function Complete reference article. Supported Browsers: Chrome 1 and aboveFirefox 1 and aboveEdge 12 and aboveOpera 3 and aboveSafari 1 and above We have a Cheat Sheet on Javascript where we covered all the important topics of Javascript to check those please go through Javascript Cheat Sheet-A Basic guide to JavaScript. Comment More infoAdvertise with us Next Article JavaScript isNaN() Function A arorakashish0911 Follow Improve Article Tags : JavaScript Web Technologies javascript-functions Similar Reads JavaScript isFinite() Function The JavaScript isFinite() function is used to check whether a number is a finite, legal number or not. It returns true for all the values except +infinity, -infinity, or NaN. Syntax: isFinite(value) Parameters: This method takes a single parameter as mentioned above and discussed below: value: It is 1 min read Underscore.js _.isNaN() Function _.isNaN() function:Â It is used to find whether the value of the object passed is NaN or not.If the object's value is NaN then the output will be true otherwise, it will be false.We can even perform addition, subtraction etc operations in this function. Syntax:Â _.isNaN(object) Parameters:It takes o 3 min read Tensorflow.js tf.isNaN() Function Tensorflow.js is an open-source library which is being developed by Google for running machine learning models as well as deep learning neural networks in the browser or node environment. The .isNaN() function is used to find the NaN elements of the stated tensor input. Syntax: Â tf.isNaN(x) Paramet 2 min read Underscore.js _.isNumber() Function Underscore.js _.isNumber() function is used to check whether the given object parameter is a number or not. If the given object is a number then it returns True value otherwise, it returns False. Syntax:_.isNumber( object );Parameters:object: This parameter holds the object element that needs to be 1 min read Lodash _.isNumber() Function Lodash _.isNumber() method is used to find whether the given value parameter is a number or not. If the given value is a number then it returns True value otherwise, it returns False.Syntax:_.isNumber(value); Parameters:value: This parameter holds the value to check.Return Value: This method returns 2 min read Like