Stage 1 Draft / August 12, 2026

Export star default

Introduction

This proposal removes the restriction that export * from cannot export a default export.

See the proposal repository for further information.

16 ECMAScript Language: Scripts and Modules

16.2 Modules

16.2.1 Module Semantics

16.2.1.7 Source Text Module Records

An ExportEntry Record is a Record that digests information about a single declarative export. Each ExportEntry Record has the fields defined in Table 1:

Table 1: ExportEntry Record Fields
Field Name Value Type Meaning
[[ExportName]] a String or null The name used to export this binding by this module.
[[ModuleRequest]] a ModuleRequest Record or null The ModuleRequest Record representing the ModuleSpecifier and import attributes of the ExportDeclaration. null if the ExportDeclaration does not have a ModuleSpecifier.
[[ImportName]] a String, null, namespace, or all-but-defaultall The name under which the desired binding is exported by the module identified by [[ModuleRequest]]. null if the ExportDeclaration does not have a ModuleSpecifier. namespace is used for export * as ns from "mod" declarations. all-but-defaultall is used for export * from "mod" declarations.
[[LocalName]] a String or 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

Table 2 gives examples of the ExportEntry record fields used to represent the syntactic export forms:

Table 2 (Informative): Export Forms Mappings to ExportEntry Records
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" all-but-defaultall null
export * as ns from "mod"; "ns" "mod" namespace null

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

16.2.1.7.1 ParseModule ( sourceText, realm, hostDefined )

The abstract operation ParseModule takes arguments sourceText (a String or a sequence of Unicode code points), realm (a Realm Record), and hostDefined (anything) and returns a Source Text Module Record or a non-empty List of SyntaxError objects. It creates a Source Text Module Record based upon the result of parsing sourceText as a Module. It performs the following steps when called:

  1. Let body be ParseText(sourceText, Module).
  2. If body is a List of errors, return body.
  3. Let requestedModules be the ModuleRequests of body.
  4. Let importEntries be the ImportEntries of body.
  5. Let importedBoundNames be ImportedLocalNames(importEntries).
  6. Let indirectExportEntries be a new empty List.
  7. Let localExportEntries be a new empty List.
  8. Let starExportEntries be a new empty List.
  9. Let exportEntries be the ExportEntries of body.
  10. For each ExportEntry Record exportEntry of exportEntries, do
    1. If exportEntry.[[ModuleRequest]] is null, then
      1. If importedBoundNames does not contain exportEntry.[[LocalName]], then
        1. Append exportEntry to localExportEntries.
      2. Else,
        1. NOTE: When exporting a binding or namespace object which was originally imported from another module, the ExportEntry Record is rewritten to match the form it would have if the binding or namespace object had been re-exported directly from the original module rather than imported then exported. This allows conflicts which arise from exporting the same binding or namespace twice under the same name through export * from to be ignored rather than being treated as ambiguous in step 9.e.iii of the ResolveExport concrete method of Source Text Module Records.
        2. Let ie be the element of importEntries whose [[LocalName]] is exportEntry.[[LocalName]].
        3. Append the ExportEntry Record { [[ModuleRequest]]: ie.[[ModuleRequest]], [[ImportName]]: ie.[[ImportName]], [[LocalName]]: null, [[ExportName]]: exportEntry.[[ExportName]] } to indirectExportEntries.
    2. Else if exportEntry.[[ImportName]] is all-but-defaultall, then
      1. Assert: exportEntry.[[ExportName]] is null.
      2. Append exportEntry to starExportEntries.
    3. Else,
      1. Append exportEntry to indirectExportEntries.
  11. Let async be body Contains await.
  12. Return Source Text Module Record { [[Realm]]: realm, [[Environment]]: empty, [[Namespace]]: empty, [[CycleRoot]]: empty, [[HasTLA]]: async, [[AsyncEvaluationOrder]]: unset, [[TopLevelCapability]]: empty, [[AsyncParentModules]]: « », [[PendingAsyncDependencies]]: empty, [[Status]]: new, [[EvaluationError]]: empty, [[HostDefined]]: hostDefined, [[ECMAScriptCode]]: body, [[Context]]: empty, [[ImportMeta]]: empty, [[RequestedModules]]: requestedModules, [[LoadedModules]]: « », [[ImportEntries]]: importEntries, [[LocalExportEntries]]: localExportEntries, [[IndirectExportEntries]]: indirectExportEntries, [[StarExportEntries]]: starExportEntries, [[DFSAncestorIndex]]: empty }.
 Note

An implementation may parse module source text and analyse it for Early Error conditions prior to the evaluation of ParseModule for that module source text. However, the reporting of any errors must be deferred until the point where this specification actually performs ParseModule upon that source text.

16.2.1.7.2 Implementation of Module Record Abstract Methods

The following are the concrete methods for Source Text Module Record that implement the corresponding Module Record abstract methods defined in Table 40.

16.2.1.7.2.1 GetExportedNames ( [ exportStarSet ] )

The GetExportedNames concrete method of a Source Text Module Record module takes optional argument exportStarSet (a List of Source Text Module Records) and returns a List of Strings. It performs the following steps when called:

  1. Assert: module.[[Status]] is not new.
  2. If exportStarSet is not present, set exportStarSet to a new empty List.
  3. If exportStarSet contains module, then
    1. Assert: We've reached the starting point of an export * circularity.
    2. Return a new empty List.
  4. Append module to exportStarSet.
  5. Let exportedNames be a new empty List.
  6. For each ExportEntry Record e of module.[[LocalExportEntries]], do
    1. Assert: module provides the direct binding for this export.
    2. Assert: e.[[ExportName]] is not null.
    3. Append e.[[ExportName]] to exportedNames.
  7. For each ExportEntry Record e of module.[[IndirectExportEntries]], do
    1. Assert: module imports a specific binding for this export.
    2. Assert: e.[[ExportName]] is not null.
    3. Append e.[[ExportName]] to exportedNames.
  8. For each ExportEntry Record e of module.[[StarExportEntries]], do
    1. Assert: e.[[ModuleRequest]] is not null.
    2. Let requestedModule be GetImportedModule(module, e.[[ModuleRequest]]).
    3. Let starNames be requestedModule.GetExportedNames(exportStarSet).
    4. For each element n of starNames, do
      1. If n is not "default", then
        1. If exportedNames does not contain n, then
          1. Append n to exportedNames.
  9. Return exportedNames.
 Note

GetExportedNames does not filter out or throw an exception for names that have ambiguous star export bindings.

16.2.1.7.2.2 ResolveExport ( exportName [ , resolveSet ] )

The ResolveExport concrete method of a Source Text Module Record module takes argument exportName (a String) and optional argument resolveSet (a List of Records with fields [[Module]] (a Module Record) and [[ExportName]] (a String)) and returns a ResolvedBinding Record, null, or ambiguous.

ResolveExport attempts to resolve an imported binding to the actual defining module and local binding name. The defining module may be the module represented by the Module Record this method was invoked on or some other module that is imported by that module. The parameter resolveSet is used to detect unresolved circular import/export paths. If a pair consisting of specific Module Record and exportName is reached that is already in resolveSet, an import circularity has been encountered. Before recursively calling ResolveExport, a pair consisting of module and exportName is added to resolveSet.

If a defining module is found, a ResolvedBinding Record { [[Module]], [[BindingName]] } is returned. This record identifies the resolved binding of the originally requested export, unless this is the export of a namespace with no local binding. In this case, [[BindingName]] will be set to namespace. If no definition was found or the request is found to be circular, null is returned. If the request is found to be ambiguous, ambiguous is returned.

It performs the following steps when called:

  1. Assert: module.[[Status]] is not new.
  2. If resolveSet is not present, set resolveSet to a new empty List.
  3. For each Record { [[Module]], [[ExportName]] } record of resolveSet, do
    1. If module and record.[[Module]] are the same Module Record and exportName is record.[[ExportName]], then
      1. Assert: This is a circular import request.
      2. Return null.
  4. Append the Record { [[Module]]: module, [[ExportName]]: exportName } to resolveSet.
  5. For each ExportEntry Record e of module.[[LocalExportEntries]], do
    1. If e.[[ExportName]] is exportName, then
      1. Assert: module provides the direct binding for this export.
      2. Return ResolvedBinding Record { [[Module]]: module, [[BindingName]]: e.[[LocalName]] }.
  6. For each ExportEntry Record e of module.[[IndirectExportEntries]], do
    1. If e.[[ExportName]] is exportName, then
      1. Assert: e.[[ModuleRequest]] is not null.
      2. Let importedModule be GetImportedModule(module, e.[[ModuleRequest]]).
      3. If e.[[ImportName]] is namespace, then
        1. Assert: module does not provide the direct binding for this export.
        2. Return ResolvedBinding Record { [[Module]]: importedModule, [[BindingName]]: namespace }.
      4. Assert: module imports a specific binding for this export.
      5. Assert: e.[[ImportName]] is a String.
      6. Return importedModule.ResolveExport(e.[[ImportName]], resolveSet).
  7. If exportName is "default", then
    1. Assert: A default export was not explicitly defined by this module.
    2. Return null.
    3. NOTE: A default export cannot be provided by an export * from "mod" declaration.
  8. Let starResolution be null.
  9. For each ExportEntry Record e of module.[[StarExportEntries]], do
    1. Assert: e.[[ModuleRequest]] is not null.
    2. Let importedModule be GetImportedModule(module, e.[[ModuleRequest]]).
    3. Let resolution be importedModule.ResolveExport(exportName, resolveSet).
    4. If resolution is ambiguous, return ambiguous.
    5. If resolution is not null, then
      1. Assert: resolution is a ResolvedBinding Record.
      2. If starResolution is null, then
        1. Set starResolution to resolution.
      3. Else,
        1. Assert: There is more than one * export that includes the requested name.
        2. If resolution.[[Module]] and starResolution.[[Module]] are not the same Module Record, return ambiguous.
        3. If resolution.[[BindingName]] is not starResolution.[[BindingName]], return ambiguous.
  10. Return starResolution.

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