Method load

lib/internal/modules/esm/hooks.js:357–474

* Provide source that is understood by one of Node's translators. * * Internally, this behaves like a backwards iterator, wherein the stack of * hooks starts at the top and each call to `nextLoad()` moves down 1 step * until it reaches the bottom or short-circuits. * @param {URL['href

(url, context = kEmptyObject)

   * @returns {Promise<{ format: ModuleFormat, source: ModuleSource }>}
   */
  async load(url, context = kEmptyObject) {
    const chain = this.#chains.load;
    const meta = {
      chainFinished: null,
      context,
      hookErrIdentifier: '',
      hookName: 'load',
      shortCircuited: false,
    };

    const validateArgs = (hookErrIdentifier, nextUrl, ctx) => {
      if (typeof nextUrl !== 'string') {
        // Non-strings can be coerced to a URL string
        // validateString() throws a less-specific error
        throw new ERR_INVALID_ARG_TYPE(
          `${hookErrIdentifier} url`,
          'a URL string',
          nextUrl,
        );
      }

      // Avoid expensive URL instantiation for known-good URLs
      if (!this.#validatedUrls.has(nextUrl)) {
        // No need to convert to string, since the type is already validated
        if (!URLCanParse(nextUrl)) {
          throw new ERR_INVALID_ARG_VALUE(
            `${hookErrIdentifier} url`,
            nextUrl,
            'should be a URL string',
          );
        }

        this.#validatedUrls.add(nextUrl);
      }

      if (ctx) { validateObject(ctx, `${hookErrIdentifier} context`); }
    };
    const validateOutput = (hookErrIdentifier, output) => {
      if (typeof output !== 'object' || output === null) { // [2]
        throw new ERR_INVALID_RETURN_VALUE(
          'an object',
          hookErrIdentifier,
          output,
        );
      }
    };

    const nextLoad = nextHookFactory(chain[chain.length - 1], meta, { validateArgs, validateOutput });

    const loaded = await nextLoad(url, defineImportAssertionAlias(context));
    const { hookErrIdentifier } = meta; // Retrieve the value after all settled

    validateOutput(hookErrIdentifier, loaded);

    if (loaded?.shortCircuit === true) { meta.shortCircuited = true; }

    if (!meta.chainFinished && !meta.shortCircuited) {
      throw new ERR_LOADER_CHAIN_INCOMPLETE(hookErrIdentifier);