ModuleBody : ModuleItemList

• It is a Syntax Error if the LexicallyDeclaredNames of ModuleItemList contains any duplicate entries.
• It is a Syntax Error if any element of the LexicallyDeclaredNames of ModuleItemList also occurs in the VarDeclaredNames of ModuleItemList.
• It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries.
• It is a Syntax Error if any element of the ExportedBindings of ModuleItemList does not also occur in either the VarDeclaredNames of ModuleItemList, or the LexicallyDeclaredNames of ModuleItemList.
• It is a Syntax Error if ModuleItemList Contains super.
• It is a Syntax Error if ModuleItemList Contains NewTarget.
• It is a Syntax Error if ContainsDuplicateLabels of ModuleItemList with argument « » is true.
• It is a Syntax Error if ContainsUndefinedBreakTarget of ModuleItemList with argument « » is true.
• It is a Syntax Error if ContainsUndefinedContinueTarget of ModuleItemList with arguments « » and « » is true.

Note

The duplicate ExportedNames rule implies that multiple export default ExportDeclaration items within a ModuleBody is a Syntax Error. Additional error conditions relating to conflicting or duplicate declarations are checked during module linking prior to evaluation of a Module. If any such errors are detected the Module is not evaluated.

With parameter labelSet.

ModuleItemList : ModuleItemList ModuleItem

1. Let hasDuplicates be ContainsDuplicateLabels of ModuleItemList with argument labelSet.
2. If hasDuplicates is true, return true.
3. Return ContainsDuplicateLabels of ModuleItem with argument labelSet.

ModuleItem : ImportDeclaration ExportDeclaration

1. Return false.

With parameter labelSet.

ModuleItemList : ModuleItemList ModuleItem

1. Let hasUndefinedLabels be ContainsUndefinedBreakTarget of ModuleItemList with argument labelSet.
2. If hasUndefinedLabels is true, return true.
3. Return ContainsUndefinedBreakTarget of ModuleItem with argument labelSet.

ModuleItem : ImportDeclaration ExportDeclaration

1. Return false.

With parameters iterationSet and labelSet.

ModuleItemList : ModuleItemList ModuleItem

1. Let hasUndefinedLabels be ContainsUndefinedContinueTarget of ModuleItemList with arguments iterationSet and « ».
2. If hasUndefinedLabels is true, return true.
3. Return ContainsUndefinedContinueTarget of ModuleItem with arguments iterationSet and « ».

ModuleItem : ImportDeclaration ExportDeclaration

1. Return false.

Note

ExportedBindings are the locally bound names that are explicitly associated with a Module's ExportedNames.

ModuleItemList : ModuleItemList ModuleItem

1. Let names be ExportedBindings of ModuleItemList.
2. Append to names the elements of the ExportedBindings of ModuleItem.
3. Return names.

ModuleItem : ImportDeclaration StatementListItem

1. Return a new empty List.

Note

ExportedNames are the externally visible names that a Module explicitly maps to one of its local name bindings.

ModuleItemList : ModuleItemList ModuleItem

1. Let names be ExportedNames of ModuleItemList.
2. Append to names the elements of the ExportedNames of ModuleItem.
3. Return names.

ModuleItem : ExportDeclaration

1. Return the ExportedNames of ExportDeclaration.

ModuleItem : ImportDeclaration StatementListItem

1. Return a new empty List.

Module : [empty]

1. Return a new empty List.

ModuleItemList : ModuleItemList ModuleItem

1. Let entries be ExportEntries of ModuleItemList.
2. Append to entries the elements of the ExportEntries of ModuleItem.
3. Return entries.

ModuleItem : ImportDeclaration StatementListItem

1. Return a new empty List.

Module : [empty]

1. Return a new empty List.

ModuleItemList : ModuleItemList ModuleItem

1. Let entries be ImportEntries of ModuleItemList.
2. Append to entries the elements of the ImportEntries of ModuleItem.
3. Return entries.

ModuleItem : ExportDeclaration StatementListItem

1. Return a new empty List.

The abstract operation ImportedLocalNames with argument importEntries creates a List of all of the local name bindings defined by a List of ImportEntry Records (see Table 40). ImportedLocalNames performs the following steps:

1. Let localNames be a new empty List.
2. For each ImportEntry Record i in importEntries, do
   1. Append i.[[LocalName]] to localNames.
3. Return localNames.

Module : [empty]

1. Return a new empty List.

ModuleItemList : ModuleItem

1. Return ModuleRequests of ModuleItem.

ModuleItemList : ModuleItemList ModuleItem

1. Let moduleNames be ModuleRequests of ModuleItemList.
2. Let additionalNames be ModuleRequests of ModuleItem.
3. Append to moduleNames each element of additionalNames that is not already an element of moduleNames.
4. Return moduleNames.

ModuleItem : StatementListItem

1. Return a new empty List.

Note 1

The LexicallyDeclaredNames of a Module includes the names of all of its imported bindings.

ModuleItemList : ModuleItemList ModuleItem

1. Let names be LexicallyDeclaredNames of ModuleItemList.
2. Append to names the elements of the LexicallyDeclaredNames of ModuleItem.
3. Return names.

ModuleItem : ImportDeclaration

1. Return the BoundNames of ImportDeclaration.

ModuleItem : ExportDeclaration

1. If ExportDeclaration is export VariableStatement, return a new empty List.
2. Return the BoundNames of ExportDeclaration.

ModuleItem : StatementListItem

1. Return LexicallyDeclaredNames of StatementListItem.

Note 2

At the top level of a Module, function declarations are treated like lexical declarations rather than like var declarations.

Module : [empty]

1. Return a new empty List.

ModuleItemList : ModuleItemList ModuleItem

1. Let declarations be LexicallyScopedDeclarations of ModuleItemList.
2. Append to declarations the elements of the LexicallyScopedDeclarations of ModuleItem.
3. Return declarations.

ModuleItem : ImportDeclaration

1. Return a new empty List.

Module : [empty]

1. Return a new empty List.

ModuleItemList : ModuleItemList ModuleItem

1. Let names be VarDeclaredNames of ModuleItemList.
2. Append to names the elements of the VarDeclaredNames of ModuleItem.
3. Return names.

ModuleItem : ImportDeclaration

1. Return a new empty List.

ModuleItem : ExportDeclaration

1. If ExportDeclaration is export VariableStatement, return BoundNames of ExportDeclaration.
2. Return a new empty List.

Module : [empty]

1. Return a new empty List.

ModuleItemList : ModuleItemList ModuleItem

1. Let declarations be VarScopedDeclarations of ModuleItemList.
2. Append to declarations the elements of the VarScopedDeclarations of ModuleItem.
3. Return declarations.

ModuleItem : ImportDeclaration

1. Return a new empty List.

ModuleItem : ExportDeclaration

1. If ExportDeclaration is export VariableStatement, return VarScopedDeclarations of VariableStatement.
2. Return a new empty List.

A Module Record encapsulates structural information about the imports and exports of a single module. This information is used to link the imports and exports of sets of connected modules. A Module Record includes four fields that are only used when evaluating a module.

For specification purposes Module Record values are values of the Record specification type and can be thought of as existing in a simple object-oriented hierarchy where Module Record is an abstract class with concrete subclasses. This specification only defines a single Module Record concrete subclass named Source Text Module Record. Other specifications and implementations may define additional Module Record subclasses corresponding to alternative module definition facilities that they defined.

Module Record defines the fields listed in Table 37. All Module Definition subclasses include at least those fields. Module Record also defines the abstract method list in Table 38. All Module definition subclasses must provide concrete implementations of these abstract methods.

Field Name	Value Type	Meaning
[[Realm]]	Realm Record | undefined	The Realm within which this module was created. undefined if not yet assigned.
[[Environment]]	Lexical Environment | undefined	The Lexical Environment containing the top level bindings for this module. This field is set when the module is instantiated.
[[Namespace]]	Object | undefined	The Module Namespace Object (26.3) if one has been created for this module. Otherwise undefined.
[[Evaluated]]	Boolean	Initially false, true if evaluation of this module has started. Remains true when evaluation completes, even if it is an abrupt completion.
[[HostDefined]]	Any, default value is undefined.	Field reserved for use by host environments that need to associate additional information with a module.

Method	Purpose
GetExportedNames(exportStarSet)	Return a list of all names that are either directly or indirectly exported from this module.
ResolveExport(exportName, resolveSet)	Return the binding of a name exported by this module. Bindings are represented by a ResolvedBinding Record, of the form {[[Module]]: Module Record, [[BindingName]]: String}. Return null if the name cannot be resolved, or "ambiguous" if multiple bindings were found.
ModuleDeclarationInstantiation()	Transitively resolve all module dependencies and create a module Environment Record for the module.
ModuleEvaluation()	Do nothing if this module has already been evaluated. Otherwise, transitively evaluate all module dependences of this module and then evaluate this module. ModuleDeclarationInstantiation must be completed prior to invoking this method.

A Source Text Module Record is used to represent information about a module that was defined from ECMAScript source text (10) that was parsed using the goal symbol Module. Its fields contain digested information about the names that are imported by the module and its concrete methods use this digest to link, instantiate, and evaluate the module.

In addition to the fields, defined in Table 37, Source Text Module Records have the additional fields listed in Table 39. Each of these fields initially has the value undefined.

Field Name	Value Type	Meaning
[[ECMAScriptCode]]	a Parse Node	The result of parsing the source text of this module using Module as the goal symbol.
[[RequestedModules]]	List of String	A List of all the ModuleSpecifier strings used by the module represented by this record to request the importation of a module. The List is source code occurrence ordered.
[[ImportEntries]]	List of ImportEntry Records	A List of ImportEntry records derived from the code of this module.
[[LocalExportEntries]]	List of ExportEntry Records	A List of ExportEntry records derived from the code of this module that correspond to declarations that occur within the module.
[[IndirectExportEntries]]	List of ExportEntry Records	A List of ExportEntry records derived from the code of this module that correspond to reexported imports that occur within the module.
[[StarExportEntries]]	List of ExportEntry Records	A List of ExportEntry records derived from the code of this module that correspond to export * declarations that occur within the module.

An ImportEntry Record is a Record that digests information about a single declarative import. Each ImportEntry Record has the fields defined in Table 40:

Field Name	Value Type	Meaning
[[ModuleRequest]]	String	String value of the ModuleSpecifier of the ImportDeclaration.
[[ImportName]]	String	The name under which the desired binding is exported by the module identified by [[ModuleRequest]]. The value "*" indicates that the import request is for the target module's namespace object.
[[LocalName]]	String	The name that is used to locally access the imported value from within the importing module.

Note 1

Table 41 gives examples of ImportEntry records fields used to represent the syntactic import forms:

Import Statement Form	[[ModuleRequest]]	[[ImportName]]	[[LocalName]]
import v from "mod";	"mod"	"default"	"v"
import * as ns from "mod";	"mod"	"*"	"ns"
import {x} from "mod";	"mod"	"x"	"x"
import {x as v} from "mod";	"mod"	"x"	"v"
import "mod";	An ImportEntry Record is not created.

An ExportEntry Record is a Record that digests information about a single declarative export. Each ExportEntry Record has the fields defined in Table 42:

Field Name	Value Type	Meaning
[[ExportName]]	String	The name used to export this binding by this module.
[[ModuleRequest]]	String | null	The String value of the ModuleSpecifier of the ExportDeclaration. null if the ExportDeclaration does not have a ModuleSpecifier.
[[ImportName]]	String | null	The name under which the desired binding is exported by the module identified by [[ModuleRequest]]. null if the ExportDeclaration does not have a ModuleSpecifier. "*" indicates that the export request is for all exported bindings.
[[LocalName]]	String | null	The name that is used to locally access the exported value from within the importing module. null if the exported value is not locally accessible from within the module.

Note 2

Table 43 gives examples of the ExportEntry record fields used to represent the syntactic export forms:

Export Statement Form	[[ExportName]]	[[ModuleRequest]]	[[ImportName]]	[[LocalName]]
export var v;	"v"	null	null	"v"
export default function f(){}	"default"	null	null	"f"
export default function(){}	"default"	null	null	"*default*"
export default 42;	"default"	null	null	"*default*"
export {x};	"x"	null	null	"x"
export {v as x};	"x"	null	null	"v"
export {x} from "mod";	"x"	"mod"	"x"	null
export {v as x} from "mod";	"x"	"mod"	"v"	null
export * from "mod";	null	"mod"	"*"	null

The following definitions specify the required concrete methods and other abstract operations for Source Text Module Records

HostResolveImportedModule is an implementation-defined abstract operation that provides the concrete Module Record subclass instance that corresponds to the ModuleSpecifier String, specifier, occurring within the context of the module represented by the Module Record referencingModule.

The implementation of HostResolveImportedModule must conform to the following requirements:

• The normal return value must be an instance of a concrete subclass of Module Record.
• If a Module Record corresponding to the pair referencingModule, specifier does not exist or cannot be created, an exception must be thrown.
• This operation must be idempotent if it completes normally. Each time it is called with a specific referencingModule, specifier pair as arguments it must return the same Module Record instance.

Multiple different referencingModule, specifier pairs may map to the same Module Record instance. The actual mapping semantic is implementation-defined but typically a normalization process is applied to specifier as part of the mapping process. A typical normalization process would include actions such as alphabetic case folding and expansion of relative and abbreviated path specifiers.

The abstract operation GetModuleNamespace called with argument module performs the following steps:

1. Assert: module is an instance of a concrete subclass of Module Record.
2. Let namespace be module.[[Namespace]].
3. If namespace is undefined, then
   1. Let exportedNames be ? module.GetExportedNames(« »).
   2. Let unambiguousNames be a new empty List.
   3. For each name that is an element of exportedNames, do
      1. Let resolution be ? module.ResolveExport(name, « »).
      2. If resolution is null, throw a SyntaxError exception.
      3. If resolution is not "ambiguous", append name to unambiguousNames.
   4. Set namespace to ModuleNamespaceCreate(module, unambiguousNames).
4. Return namespace.

A TopLevelModuleEvaluationJob with parameters sourceText and hostDefined is a job that parses, validates, and evaluates sourceText as a Module.

1. Assert: sourceText is an ECMAScript source text (see clause 10).
2. Let realm be the current Realm Record.
3. Let m be ParseModule(sourceText, realm, hostDefined).
4. If m is a List of errors, then
   1. Perform HostReportErrors(m).
   2. Return NormalCompletion(undefined).
5. Perform ? m.ModuleDeclarationInstantiation().
6. Assert: All dependencies of m have been transitively resolved and m is ready for evaluation.
7. Return ? m.ModuleEvaluation().

Note

An implementation may parse a sourceText as a Module, analyse it for Early Error conditions, and instantiate it prior to the execution of the TopLevelModuleEvaluationJob for that sourceText. An implementation may also resolve, pre-parse and pre-analyse, and pre-instantiate module dependencies of sourceText. However, the reporting of any errors detected by these actions must be deferred until the TopLevelModuleEvaluationJob is actually executed.

Module : [empty]

1. Return NormalCompletion(undefined).

ModuleBody : ModuleItemList

1. Let result be the result of evaluating ModuleItemList.
2. If result.[[Type]] is normal and result.[[Value]] is empty, then
   1. Return NormalCompletion(undefined).
3. Return Completion(result).

ModuleItemList : ModuleItemList ModuleItem

1. Let sl be the result of evaluating ModuleItemList.
2. ReturnIfAbrupt(sl).
3. Let s be the result of evaluating ModuleItem.
4. Return Completion(UpdateEmpty(s, sl.[[Value]])).

Note

The value of a ModuleItemList is the value of the last value producing item in the ModuleItemList.

ModuleItem : ImportDeclaration

1. Return NormalCompletion(empty).

ModuleItem : ImportDeclaration

• It is a Syntax Error if the BoundNames of ImportDeclaration contains any duplicate entries.

ImportDeclaration : import ImportClause FromClause ;

1. Return the BoundNames of ImportClause.

ImportDeclaration : import ModuleSpecifier ;

1. Return a new empty List.

ImportClause : ImportedDefaultBinding , NameSpaceImport

1. Let names be the BoundNames of ImportedDefaultBinding.
2. Append to names the elements of the BoundNames of NameSpaceImport.
3. Return names.

ImportClause : ImportedDefaultBinding , NamedImports

1. Let names be the BoundNames of ImportedDefaultBinding.
2. Append to names the elements of the BoundNames of NamedImports.
3. Return names.

NamedImports : { }

1. Return a new empty List.

ImportsList : ImportsList , ImportSpecifier

1. Let names be the BoundNames of ImportsList.
2. Append to names the elements of the BoundNames of ImportSpecifier.
3. Return names.

ImportSpecifier : IdentifierName as ImportedBinding

1. Return the BoundNames of ImportedBinding.

ImportDeclaration : import ImportClause FromClause ;

1. Let module be the sole element of ModuleRequests of FromClause.
2. Return ImportEntriesForModule of ImportClause with argument module.

ImportDeclaration : import ModuleSpecifier ;

1. Return a new empty List.

With parameter module.

ImportClause : ImportedDefaultBinding , NameSpaceImport

1. Let entries be ImportEntriesForModule of ImportedDefaultBinding with argument module.
2. Append to entries the elements of the ImportEntriesForModule of NameSpaceImport with argument module.
3. Return entries.

ImportClause : ImportedDefaultBinding , NamedImports

1. Let entries be ImportEntriesForModule of ImportedDefaultBinding with argument module.
2. Append to entries the elements of the ImportEntriesForModule of NamedImports with argument module.
3. Return entries.

ImportedDefaultBinding : ImportedBinding

1. Let localName be the sole element of BoundNames of ImportedBinding.
2. Let defaultEntry be the ImportEntry Record {[[ModuleRequest]]: module, [[ImportName]]: "default", [[LocalName]]: localName }.
3. Return a new List containing defaultEntry.

NameSpaceImport : * as ImportedBinding

1. Let localName be the StringValue of ImportedBinding.
2. Let entry be the ImportEntry Record {[[ModuleRequest]]: module, [[ImportName]]: "*", [[LocalName]]: localName }.
3. Return a new List containing entry.

NamedImports : { }

1. Return a new empty List.

ImportsList : ImportsList , ImportSpecifier

1. Let specs be the ImportEntriesForModule of ImportsList with argument module.
2. Append to specs the elements of the ImportEntriesForModule of ImportSpecifier with argument module.
3. Return specs.

ImportSpecifier : ImportedBinding

1. Let localName be the sole element of BoundNames of ImportedBinding.
2. Let entry be the ImportEntry Record {[[ModuleRequest]]: module, [[ImportName]]: localName, [[LocalName]]: localName }.
3. Return a new List containing entry.

ImportSpecifier : IdentifierName as ImportedBinding

1. Let importName be the StringValue of IdentifierName.
2. Let localName be the StringValue of ImportedBinding.
3. Let entry be the ImportEntry Record {[[ModuleRequest]]: module, [[ImportName]]: importName, [[LocalName]]: localName }.
4. Return a new List containing entry.

ImportDeclaration : import ImportClause FromClause ;

1. Return ModuleRequests of FromClause.

ModuleSpecifier : StringLiteral

1. Return a List containing the StringValue of StringLiteral.

ExportDeclaration : export ExportClause ;

• For each IdentifierName n in ReferencedBindings of ExportClause: It is a Syntax Error if StringValue of n is a ReservedWord or if the StringValue of n is one of: "implements", "interface", "let", "package", "private", "protected", "public", or "static".

Note

The above rule means that each ReferencedBindings of ExportClause is treated as an IdentifierReference.

ExportDeclaration : export * FromClause ; export ExportClause FromClause ; export ExportClause ;

1. Return a new empty List.

ExportDeclaration : export VariableStatement

1. Return the BoundNames of VariableStatement.

ExportDeclaration : export Declaration

1. Return the BoundNames of Declaration.

ExportDeclaration : export default HoistableDeclaration

1. Let declarationNames be the BoundNames of HoistableDeclaration.
2. If declarationNames does not include the element "*default*", append "*default*" to declarationNames.
3. Return declarationNames.

ExportDeclaration : export default ClassDeclaration

1. Let declarationNames be the BoundNames of ClassDeclaration.
2. If declarationNames does not include the element "*default*", append "*default*" to declarationNames.
3. Return declarationNames.

ExportDeclaration : export default AssignmentExpression ;

1. Return « "*default*" ».

ExportDeclaration : export ExportClause FromClause ; export * FromClause ;

1. Return a new empty List.

ExportDeclaration : export ExportClause ;

1. Return the ExportedBindings of ExportClause.

ExportDeclaration : export VariableStatement

1. Return the BoundNames of VariableStatement.

ExportDeclaration : export Declaration

1. Return the BoundNames of Declaration.

ExportDeclaration : export default HoistableDeclaration ExportDeclaration : export default ClassDeclaration ExportDeclaration : export default AssignmentExpression ;

1. Return the BoundNames of this ExportDeclaration.

ExportClause : { }

1. Return a new empty List.

ExportsList : ExportsList , ExportSpecifier

1. Let names be the ExportedBindings of ExportsList.
2. Append to names the elements of the ExportedBindings of ExportSpecifier.
3. Return names.

ExportSpecifier : IdentifierName

1. Return a List containing the StringValue of IdentifierName.

ExportSpecifier : IdentifierName as IdentifierName

1. Return a List containing the StringValue of the first IdentifierName.

ExportDeclaration : export * FromClause ;

1. Return a new empty List.

ExportDeclaration : export ExportClause FromClause ; ExportDeclaration : export ExportClause ;

1. Return the ExportedNames of ExportClause.

ExportDeclaration : export VariableStatement

1. Return the BoundNames of VariableStatement.

ExportDeclaration : export Declaration

1. Return the BoundNames of Declaration.

ExportDeclaration : export default HoistableDeclaration ExportDeclaration : export default ClassDeclaration ExportDeclaration : export default AssignmentExpression ;

1. Return « "default" ».

ExportClause : { }

1. Return a new empty List.

ExportsList : ExportsList , ExportSpecifier

1. Let names be the ExportedNames of ExportsList.
2. Append to names the elements of the ExportedNames of ExportSpecifier.
3. Return names.

ExportSpecifier : IdentifierName

1. Return a List containing the StringValue of IdentifierName.

ExportSpecifier : IdentifierName as IdentifierName

1. Return a List containing the StringValue of the second IdentifierName.

ExportDeclaration : export * FromClause ;

1. Let module be the sole element of ModuleRequests of FromClause.
2. Let entry be the ExportEntry Record {[[ModuleRequest]]: module, [[ImportName]]: "*", [[LocalName]]: null, [[ExportName]]: null }.
3. Return a new List containing entry.

ExportDeclaration : export ExportClause FromClause ;

1. Let module be the sole element of ModuleRequests of FromClause.
2. Return ExportEntriesForModule of ExportClause with argument module.

ExportDeclaration : export ExportClause ;

1. Return ExportEntriesForModule of ExportClause with argument null.

ExportDeclaration : export VariableStatement

1. Let entries be a new empty List.
2. Let names be the BoundNames of VariableStatement.
3. For each name in names, do
   1. Append the ExportEntry Record {[[ModuleRequest]]: null, [[ImportName]]: null, [[LocalName]]: name, [[ExportName]]: name } to entries.
4. Return entries.

ExportDeclaration : export Declaration

1. Let entries be a new empty List.
2. Let names be the BoundNames of Declaration.
3. For each name in names, do
   1. Append the ExportEntry Record {[[ModuleRequest]]: null, [[ImportName]]: null, [[LocalName]]: name, [[ExportName]]: name } to entries.
4. Return entries.

ExportDeclaration : export default HoistableDeclaration

1. Let names be BoundNames of HoistableDeclaration.
2. Let localName be the sole element of names.
3. Return a new List containing the ExportEntry Record {[[ModuleRequest]]: null, [[ImportName]]: null, [[LocalName]]: localName, [[ExportName]]: "default"}.

ExportDeclaration : export default ClassDeclaration

1. Let names be BoundNames of ClassDeclaration.
2. Let localName be the sole element of names.
3. Return a new List containing the ExportEntry Record {[[ModuleRequest]]: null, [[ImportName]]: null, [[LocalName]]: localName, [[ExportName]]: "default"}.

ExportDeclaration : export default AssignmentExpression ;

1. Let entry be the ExportEntry Record {[[ModuleRequest]]: null, [[ImportName]]: null, [[LocalName]]: "*default*", [[ExportName]]: "default"}.
2. Return a new List containing entry.

Note

"*default*" is used within this specification as a synthetic name for anonymous default export values.

With parameter module.

ExportClause : { }

1. Return a new empty List.

ExportsList : ExportsList , ExportSpecifier

1. Let specs be the ExportEntriesForModule of ExportsList with argument module.
2. Append to specs the elements of the ExportEntriesForModule of ExportSpecifier with argument module.
3. Return specs.

ExportSpecifier : IdentifierName

1. Let sourceName be the StringValue of IdentifierName.
2. If module is null, then
   1. Let localName be sourceName.
   2. Let importName be null.
3. Else,
   1. Let localName be null.
   2. Let importName be sourceName.
4. Return a new List containing the ExportEntry Record {[[ModuleRequest]]: module, [[ImportName]]: importName, [[LocalName]]: localName, [[ExportName]]: sourceName }.

ExportSpecifier : IdentifierName as IdentifierName

1. Let sourceName be the StringValue of the first IdentifierName.
2. Let exportName be the StringValue of the second IdentifierName.
3. If module is null, then
   1. Let localName be sourceName.
   2. Let importName be null.
4. Else,
   1. Let localName be null.
   2. Let importName be sourceName.
5. Return a new List containing the ExportEntry Record {[[ModuleRequest]]: module, [[ImportName]]: importName, [[LocalName]]: localName, [[ExportName]]: exportName }.

ExportDeclaration : export * FromClause ; export ExportClause FromClause ; export ExportClause ; export default AssignmentExpression ;

1. Return false.

Note

It is not necessary to treat export default AssignmentExpression as a constant declaration because there is no syntax that permits assignment to the internal bound name used to reference a module's default object.

ExportDeclaration : export * FromClause ; export ExportClause FromClause ; export ExportClause ; export VariableStatement

1. Return a new empty List.

ExportDeclaration : export Declaration

1. Return a new List containing DeclarationPart of Declaration.

ExportDeclaration : export default HoistableDeclaration

1. Return a new List containing DeclarationPart of HoistableDeclaration.

ExportDeclaration : export default ClassDeclaration

1. Return a new List containing ClassDeclaration.

ExportDeclaration : export default AssignmentExpression ;

1. Return a new List containing this ExportDeclaration.

ExportDeclaration : export * FromClause ; ExportDeclaration : export ExportClause FromClause ;

1. Return the ModuleRequests of FromClause.

ExportDeclaration : export ExportClause ; export VariableStatement export Declaration export default HoistableDeclaration export default ClassDeclaration export default AssignmentExpression ;

1. Return a new empty List.

ExportClause : { }

1. Return a new empty List.

ExportsList : ExportsList , ExportSpecifier

1. Let names be the ReferencedBindings of ExportsList.
2. Append to names the elements of the ReferencedBindings of ExportSpecifier.
3. Return names.

ExportSpecifier : IdentifierName

1. Return a List containing the IdentifierName.

ExportSpecifier : IdentifierName as IdentifierName

1. Return a List containing the first IdentifierName.

ExportDeclaration : export * FromClause ; export ExportClause FromClause ; export ExportClause ;

1. Return NormalCompletion(empty).

ExportDeclaration : export VariableStatement

1. Return the result of evaluating VariableStatement.

ExportDeclaration : export Declaration

1. Return the result of evaluating Declaration.

ExportDeclaration : export default HoistableDeclaration

1. Return the result of evaluating HoistableDeclaration.

ExportDeclaration : export default ClassDeclaration

1. Let value be the result of BindingClassDeclarationEvaluation of ClassDeclaration.
2. ReturnIfAbrupt(value).
3. Let className be the sole element of BoundNames of ClassDeclaration.
4. If className is "*default*", then
   1. Let hasNameProperty be ? HasOwnProperty(value, "name").
   2. If hasNameProperty is false, perform SetFunctionName(value, "default").
   3. Let env be the running execution context's LexicalEnvironment.
   4. Perform ? InitializeBoundName("*default*", value, env).
5. Return NormalCompletion(empty).

ExportDeclaration : export default AssignmentExpression ;

1. Let rhs be the result of evaluating AssignmentExpression.
2. Let value be ? GetValue(rhs).
3. If IsAnonymousFunctionDefinition(AssignmentExpression) is true, then
   1. Let hasNameProperty be ? HasOwnProperty(value, "name").
   2. If hasNameProperty is false, perform SetFunctionName(value, "default").
4. Let env be the running execution context's LexicalEnvironment.
5. Perform ? InitializeBoundName("*default*", value, env).
6. Return NormalCompletion(empty).