Data URL modules

Node loads data: modules directly from their URL payload. Supported ESM media types include text/javascript, application/json, and application/wasm (Node ESM documentation).

Query and fragment handling

Before Node 22.9.0, the ESM loader parsed a data module from url.pathname, so URL query and fragment metadata were outside the module body (v20.20.2 loader). Node 22.9.0 adopted the Fetch-standard data-URL processor (backport); it serializes the URL with only the fragment excluded, then decodes the remaining body (v22.9.0 processor).

Appending a query to a base64 data URL therefore changes its encoded body on Node 22.9.0 and newer. For example, data:text/javascript;base64,Y29uc29sZS5sb2coMSk=?namespace=private is not valid base64. A fragment leaves the payload unchanged because the processor excludes it.

Loader implication

Loader metadata that must survive into imports from a data: module belongs in its fragment, not a query parameter. A data: module can import absolute URLs, so preserving the metadata is necessary for a hook to continue handling a TypeScript child module. Relative imports remain unsupported because data: is not a special URL scheme.