Function transform

packages/yaml/src/index.js:30–54

(content, id)

    name: 'yaml',

    transform(content, id) {
      if (!extensions.some((ext) => id.toLowerCase().endsWith(ext))) return null;
      if (!filter(id)) return null;

      let data = loadMethod(content);

      if (typeof options.transform === 'function') {
        const result = options.transform(data, id);
        // eslint-disable-next-line no-undefined
        if (result !== undefined) {
          data = result;
        }
      }

      const keys = Object.keys(data).filter((key) => key === makeLegalIdentifier(key));
      const code = `var data = ${toSource(data)};\n\n`;
      const exports = ['export default data;']
        .concat(keys.map((key) => `export var ${key} = data.${key};`))
        .join('\n');

      return {
        code: code + exports,
        map: { mappings: '' }
      };
    }
  };
}