JavaScript: NaN

Last update on May 28 2022 10:32:23 (UTC/GMT +8 hours)

Description

NaN is a value represents not a number.

NaN is a top level property and is not associated with any object.

NaN is never equal to any other number, including NaN itself. It is not possible to check whether a value is a number by comparing it with NaN using equal to operator. You have to use the isNaN function instead.

Methods like Number constructor, parseFloat, and parseInt return NaN if the argument passed to them are not numbers.

NaN property can be used to refer an error for a function, provided the function returns a valid number.

Syntax

NaN

Example of JavaScript NAN - when math function fails

JavaScript Code:

console.log(Math.abs('MyString'));

View example of JavaScript NAN - when math function fails

Live demo:

See the Pen nan-property-1 by w3resource (@w3resource) on CodePen.

JavaScript Code:

console.log(parseInt("xyz"));

View Example JavaScript NAN - when a function tries to read a number fails

Live demo:

See the Pen nan-property-2 by w3resource (@w3resource) on CodePen.

Note

Since Equality operator (i.e. == and ===) cannot be used to test a value against NaN, If you wish to perform such a test, use isNAN instead of NAN.

See the Pen javascript-common-editor by w3resource (@w3resource) on CodePen.

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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