Why typeof NaN === "number"

This is one of JavaScript's most confusing aspects. Let's explore why.

The Typeof Operator

The typeof operator returns the type of a value. For NaN, it returns "number", which seems contradictory.

Historical Reasons

This behavior exists for historical reasons. NaN was designed to be a numeric value that represents "not a number" in mathematical operations.

The Reality

Even though NaN means "Not a Number", it's technically a numeric type in JavaScript. It's a special floating-point value.

Practical Implications

Understanding this helps you write better error handling and type checking code.