Function resolvePackageTargetString

lib/internal/modules/esm/resolve.js:377–456

* Resolves the package target string to a URL object. * @param {string} target - The target string to resolve. * @param {string} subpath - The subpath to append to the resolved URL. * @param {RegExpMatchArray} match - The matched string array from the import statement. * @param {string} packageJ

(
  target,
  subpath,
  match,
  packageJSONUrl,
  base,
  pattern,
  internal,
  isPathMap,
  conditions,
)

 * @throws {ERR_INVALID_SUBPATH} - If the subpath is invalid.
 */
function resolvePackageTargetString(
  target,
  subpath,
  match,
  packageJSONUrl,
  base,
  pattern,
  internal,
  isPathMap,
  conditions,
) {

  if (subpath !== '' && !pattern && target[target.length - 1] !== '/') {
    throw invalidPackageTarget(match, target, packageJSONUrl, internal, base);
  }

  if (!StringPrototypeStartsWith(target, './')) {
    if (internal &&
        target[0] !== '/' &&
        !StringPrototypeStartsWith(target, '../')) {
      // No need to convert target to string, since it's already presumed to be
      if (!URLCanParse(target)) {
        const exportTarget = pattern ?
          RegExpPrototypeSymbolReplace(patternRegEx, target, () => subpath) :
          target + subpath;
        return packageResolve(
          exportTarget, packageJSONUrl, conditions);
      }
    }
    throw invalidPackageTarget(match, target, packageJSONUrl, internal, base);
  }

  if (RegExpPrototypeExec(invalidSegmentRegEx, StringPrototypeSlice(target, 2)) !== null) {
    if (RegExpPrototypeExec(deprecatedInvalidSegmentRegEx, StringPrototypeSlice(target, 2)) === null) {
      if (!isPathMap) {
        const request = pattern ?
          StringPrototypeReplace(match, '*', () => subpath) :
          match + subpath;
        const resolvedTarget = pattern ?
          RegExpPrototypeSymbolReplace(patternRegEx, target, () => subpath) :
          target;
        emitInvalidSegmentDeprecation(resolvedTarget, request, match, packageJSONUrl, internal, base, true);
      }
    } else {
      throw invalidPackageTarget(match, target, packageJSONUrl, internal, base);
    }
  }

  const resolved = new URL(target, packageJSONUrl);
  const resolvedPath = resolved.pathname;
  const packagePath = new URL('.', packageJSONUrl).pathname;

  if (!StringPrototypeStartsWith(resolvedPath, packagePath)) {
    throw invalidPackageTarget(match, target, packageJSONUrl, internal, base);
  }

  if (subpath === '') { return resolved; }