files/en-us/web/javascript/reference/global_objects/number/nan/index.md

metadata

title: Number.NaN
short-title: NaN
slug: Web/JavaScript/Reference/Global_Objects/Number/NaN
page-type: javascript-static-data-property
browser-compat: javascript.builtins.Number.NaN
sidebar: jsref

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

{{InteractiveExample("JavaScript Demo: Number.NaN", "taller")}}

function clean(x) {
  if (x === Number.NaN) {
    // Can never be true
    return null;
  }
  if (isNaN(x)) {
    return 0;
  }
}

console.log(clean(Number.NaN));
// Expected output: 0

Value

The number value {{jsxref("NaN")}}.

{{js_property_attributes(0, 0, 0)}}

Description

Because NaN is a static property of {{jsxref("Number")}}, you always use it as Number.NaN, rather than as a property of a number value.

Examples

Checking whether values are numeric

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

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{jsxref("NaN")}}
• {{jsxref("Number.isNaN()")}}