How Can I Reliably Check for NaN Values in JavaScript?

Understanding NaN in JavaScript: Identifying Not-a-Number Values

In JavaScript, parsing a non-numeric value using parseFloat will result in NaN, which represents "Not-a-Number." While attempting to compare NaN with itself or Number.NaN may seem intuitive, these methods will not yield the expected true result.

The Solution: Utilize the isNaN Function

To correctly determine if a value is NaN, employ the isNaN function. This function exclusively returns true for NaN values, regardless of their origin.

isNaN(parseFloat("geoff")); // true

Note: The isNaN function can be used to check for NaN in any value, including non-numeric types.

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