Annotated ECMAScript 5.1
‟Ex igne vita”
‟Ex igne vita”
The strict mode restriction and exceptions
implements", "interface",
"let", "package", "private",
"protected", "public", "static", and
"yield" are classified as FutureReservedWord tokens
within strict mode code. (7.6.12 [?]).A conforming implementation, when processing strict mode code, may not extend the syntax of NumericLiteral (7.8.3) to include OctalIntegerLiteral as described in B.1.1.
A conforming implementation, when processing strict mode code (see 10.1.1), may not extend the syntax of EscapeSequence to include OctalEscapeSequence as described in B.1.2.
Assignment
to an undeclared identifier or otherwise unresolvable reference
does not create a property in the global object. When a simple
assignment occurs within strict mode code, its LeftHandSide must not evaluate to an
unresolvable Reference. If it does a ReferenceError
exception is thrown (8.7.2). The LeftHandSide also
may not be a reference to a data property with the attribute value
{[[Writable]]:false},
to an accessor property with the attribute value
{[[Set]]:undefined},
nor to a non-existent
property of an object whose [[Extensible]] internal property has
the value false.
In these cases a TypeError
exception is thrown (11.13.1).
The
identifier eval
or arguments
may not appear as the LeftHandSideExpression
of an Assignment operator (11.13) or of a PostfixExpression
(11.3) or as the UnaryExpression
operated upon by a Prefix Increment (11.4.4) or a Prefix Decrement
(11.4.5) operator.
Arguments
objects for strict mode functions define non-configurable accessor
properties named "caller"
and "callee"
which throw a TypeError exception on access
(10.6).
Arguments objects for strict mode functions do not dynamically share their array indexed property values with the corresponding formal parameter bindings of their functions. (10.6).
For
strict mode functions, if an arguments object is created the
binding of the local identifier arguments
to the arguments object is immutable and hence may not be the
target of an assignment expression. (10.5).
It is a SyntaxError if strict mode code contains an ObjectLiteral with more than one definition of any data property (11.1.5).
It
is a SyntaxError
if the Identifier
"eval"
or the Identifier "arguments"
occurs as the Identifier
in a PropertySetParameterList
of a
PropertyAssignment
that is contained in strict code or
if its FunctionBody is
strict code (11.1.5).
Strict mode eval code cannot instantiate variables or functions in the variable environment of the caller to eval. Instead, a new variable environment is created and that environment is used for declaration binding instantiation for the eval code (10.4.2).
If
this
is evaluated within strict mode code, then the this
value is not coerced to
an object. A this
value of null
or undefined
is not converted to the global object and primitive values are not
converted to wrapper objects. The this
value passed via a function call (including calls made using
Function.prototype.apply
and Function.prototype.call)
do not coerce the passed this value to an object (10.4.3, 11.1.1,
15.3.4.3, 15.3.4.4).
When
a delete
operator occurs within strict mode code,
a SyntaxError is thrown if its
UnaryExpression is a
direct reference to a variable, function argument, or function
name(11.4.1).
When
a delete
operator occurs within strict mode code, a TypeError
is thrown if the property to
be deleted has the attribute { [[Configurable]]:false
} (11.4.1).
It
is a SyntaxError
if a VariableDeclaration
or VariableDeclarationNoIn
occurs within strict code and its Identifier
is eval
or
arguments
(12.2.1).
Strict mode code may not include a WithStatement. The occurrence of a WithStatement in such a context is an SyntaxError (12.10).
It
is a SyntaxError if a TryStatement
with a Catch
occurs within strict code and the Identifier
of the Catch
production is eval
or arguments
(12.14.1)
It
is a SyntaxError if the identifier eval
or arguments
appears within a FormalParameterList
of a strict mode FunctionDeclaration
or FunctionExpression
(13.1)
A
strict mode function may not have two or more formal parameters
that have the same name. An attempt to create such a function using
a FunctionDeclaration,
FunctionExpression, or
Function
constructor is a SyntaxError
(13.1, 15.3.2).
An
implementation may not extend, beyond that defined in this specification,
meanings within strict mode functions of properties named caller
or arguments
of function instances. ECMAScript code may not create or modify
properties with these names on function objects that correspond to
strict mode functions
(10.6, 13.2, 15.3.4.5.3).
It
is a SyntaxError
to use within strict mode code the identifiers eval
or arguments
as the Identifier of a
FunctionDeclaration or
FunctionExpression or
as a formal parameter name (13.1). Attempting to dynamically define
such a strict mode function using the Function
constructor (15.3.2) will throw a SyntaxError
exception.