MSDN Library

NaN Constant (JavaScript)

Returns the special value NaN indicating that an expression is not a number.


The NaN constant (not a number) is a member of the Global object, and is made available when the scripting engine is initialized.

The NaN property was introduced in Internet Explorer before Internet Explorer 6, and was made read-only in Internet Explorer 9 standards mode.

Applies To: Global Object (JavaScript)

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