Function createIsExternal

packages/vite/src/node/external.ts:127–147

(
  environment: Environment,
)

}

function createIsExternal(
  environment: Environment,
): (id: string, importer?: string) => boolean {
  const processedIds = new Map<string, boolean>()

  const isConfiguredAsExternal = createIsConfiguredAsExternal(environment)

  return (id: string, importer?: string) => {
    if (processedIds.has(id)) {
      return processedIds.get(id)!
    }
    let isExternal = false
    if (id[0] !== '.' && !path.isAbsolute(id)) {
      isExternal =
        isBuiltin(environment.config.resolve.builtins, id) ||
        isConfiguredAsExternal(id, importer)
    }
    processedIds.set(id, isExternal)
    return isExternal
  }
}

export function canExternalizeFile(filePath: string): boolean {
  const ext = path.extname(filePath)