Callable objects that are defined in this specification only return a normal completion or a throw completion. Returning any other kind of Completion Record is considered an editorial error.
-Implementation-defined callable objects must return either a normal completion or a throw completion.
+Functions that are defined in this specification only return a normal completion or a throw completion. Returning any other kind of Completion Record is considered an editorial error.
+Implementation-defined functions must return either a normal completion or a throw completion.
There are certain built-in objects available whenever an ECMAScript |Script| or |Module| begins execution. One, the global object, is part of the global environment of the executing program. Others are accessible as initial properties of the global object or indirectly as properties of accessible built-in objects.
-Unless specified otherwise, a built-in object that is callable as a function is a built-in function object with the characteristics described in
Unless specified otherwise, a built-in object that is a function is a built-in function object with the characteristics described in
Many built-in objects are functions: they can be invoked with arguments. Some of them furthermore are constructors: they are functions intended for use with the `new` operator. For each built-in function, this specification describes the arguments required by that function and the properties of that function object. For each built-in constructor, this specification furthermore describes properties of the prototype object of that constructor and properties of specific object instances returned by a `new` expression that invokes that constructor.
Unless otherwise specified in the description of a particular function, if a built-in function or constructor is given fewer arguments than the function is specified to require, the function or constructor shall behave exactly as if it had been given sufficient additional arguments, each such argument being the *undefined* value. Such missing arguments are considered to be “not present” and may be identified in that manner by specification algorithms. In the description of a particular function, the terms “*this* value” and “NewTarget” have the meanings given in
Unless otherwise specified in the description of a particular function, if a built-in function or constructor described is given more arguments than the function is specified to allow, the extra arguments are evaluated by the call and then ignored by the function. However, an implementation may define implementation specific behaviour relating to such arguments as long as the behaviour is not the throwing of a *TypeError* exception that is predicated simply on the presence of an extra argument.