Number.NaN

The Number.NaN static data property represents Not-A-Number, which is equivalent to NaN. For more information about the behaviors of NaN, see the description for the global property.

Try it

Value

The number value NaN.

Property attributes of Number.NaN
Writable no
Enumerable no
Configurable no

Description

Because NaN is a static property of Number, you always use it as Number.NaN, rather than as a property of a number value.

Examples

Checking whether values are numeric

js
function sanitize(x) {
  if (isNaN(x)) {
    return Number.NaN;
  }
  return x;
}

Specifications

Specification
ECMAScript Language Specification
# sec-number.nan

Browser compatibility

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See also