15.3.5.1 function.length

2010-07-04

The length property of a built-in function is equal to the number of required and optional parameters according to the specification, unless stated otherwise.

For host functions, an implementation dependent value is assigned.

Functions created at parse or runtime have a length property with as value the number of formal parameters in the definition, whether they be used or not.

The property has PD{[[Writable]]:false, [[Enumerable]]:false, [[Configurable]]:false}.