The Number.NaN property represents Not-A-Number. Equivalent of NaN.

Try it

You do not have to create a Number object to access this static property (use Number.NaN).

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


Checking whether values are numeric

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

Testing against NaN

See Testing against NaN on the NaN page.


ECMAScript Language Specification
# sec-number.nan

Browser compatibility

BCD tables only load in the browser

See also

  • The global NaN object.
  • The Number object it belongs to.