Module module_resolver 

Module Resolution Implementation

This module implements TypeScript’s module resolution algorithms:

• Node (classic Node.js resolution)
• Node16/NodeNext (modern Node.js with ESM support)
• Bundler (for webpack/vite-style resolution)

The resolver handles:

• Relative imports (./foo, ../bar)
• Bare specifiers (lodash, @scope/pkg)
• Path mapping from tsconfig (paths, baseUrl)
• Package.json exports/imports fields
• TypeScript-specific extensions (.ts, .tsx, .d.ts)

Resolver invariants:

• Module existence truth comes from resolve_with_kind outcomes.
• Diagnostic code selection for module-not-found family (TS2307/TS2792/TS2834/TS2835/TS5097/TS2732) is owned here and propagated to checker via resolution records.
• Callers should not recompute not-found codes/messages from partial checker state.

Structs

ModuleResolver

Module resolver that implements TypeScript’s resolution algorithms

ResolvedModule

Result of module resolution

Enums

ImportKind

Import syntax kind - determines which error codes to use for extensionless imports in Node16/NodeNext resolution.

ImportingModuleKind

Module kind for the importing file Determines whether to use “import” or “require” conditions

ModuleExtension

Module file extensions TypeScript can resolve

PackageType

Package type from package.json “type” field Used for ESM vs CommonJS distinction in Node16/NodeNext

ResolutionFailure

Reason why module resolution failed

Constants

CANNOT_FIND_MODULE

TS2307: Cannot find module

IMPORT_PATH_NEEDS_EXTENSION

TS2834: Relative import paths need explicit file extensions in EcmaScript imports

IMPORT_PATH_NEEDS_EXTENSION_SUGGESTION

IMPORT_PATH_TS_EXTENSION_NOT_ALLOWED

JSON_MODULE_WITHOUT_RESOLVE_JSON_MODULE

TS2732: Cannot find module. Consider using ‘–resolveJsonModule’ to import module with ‘.json’ extension.

MODULE_RESOLUTION_MODE_MISMATCH

TS2792: Cannot find module. Did you mean to set the ‘moduleResolution’ option to ‘nodenext’?

MODULE_WAS_RESOLVED_TO_BUT_JSX_NOT_SET