What is nan in js

NaN (Not a Number) represents an invalid value in JavaScript, which is a special value that cannot be interpreted as a number. NaN usually results from doing math on non-numeric strings, doing math on null or undefined values, trying to convert a non-number to a number, or performing invalid operations on numbers. Use the isNaN() function to check whether a value is NaN, which has the special properties of not being equal to any other value (including itself), not being comparable via comparison operators, and being the only non-finite value. When handling NaN, you can check the input, use the isNaN() function to identify and handle, use default values ​​or fallback logic, etc.

What is NaN?

NaN (Not a Number) represents an invalid value in JavaScript. It is a special numeric value that indicates a value that cannot be interpreted as a number.

How is NaN generated?

The following are some common situations that cause NaN to occur:

• Perform mathematical operations on non-numeric strings, for example: "hello" 1
• Perform mathematical operations on null or undefined values, for example: undefined * 5
• Attempt to convert non-numbers to numbers, for example: parseInt(" foo")
• Perform an invalid operation on a number, for example: Math.sqrt(-1)

Recognize NaN

You can use the isNaN() function to check whether a value is NaN. This function returns a Boolean value indicating whether the value is NaN:

<code class="javascript">console.log(isNaN(NaN)); // true
console.log(isNaN(123)); // false</code>

Special properties of NaN

NaN has the following special properties:

• NaN is not equal to any other value, including itself: NaN !== NaN
• NaN cannot be passed through comparison operators (==, !=, >, <, > =, <=) to any other value
• NaN is the only non-finite (not positive or negative infinity) value in JavaScript

Handling NaN

When you encounter NaN, here are some steps you can take:

• Check the input and make sure all values ​​are valid numbers
• Use isNaN() Function identifies and handles NaN values
• Use default values ​​or alternate logic to handle NaN values

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