Function dataToEsm

packages/pluginutils/src/dataToEsm.ts:78–157

(data, options = {})

const identifierNameRE = /^[$_\p{ID_Start}][$\u200c\u200d\p{ID_Continue}]*$/u;

const dataToEsm: DataToEsm = function dataToEsm(data, options = {}) {
  const t = options.compact ? '' : 'indent' in options ? options.indent : '\t';
  const _ = options.compact ? '' : ' ';
  const n = options.compact ? '' : '\n';
  const declarationType = options.preferConst ? 'const' : 'var';

  if (
    options.namedExports === false ||
    typeof data !== 'object' ||
    Array.isArray(data) ||
    data instanceof Date ||
    data instanceof RegExp ||
    data === null
  ) {
    const code = serialize(data, options.compact ? null : t, '');
    const magic = _ || (/^[{[\-\/]/.test(code) ? '' : ' '); // eslint-disable-line no-useless-escape
    return `export default${magic}${code};`;
  }

  let maxUnderbarPrefixLength = 0;
  for (const key of Object.keys(data)) {
    const underbarPrefixLength = /^(_+)/.exec(key)?.[0].length ?? 0;
    if (underbarPrefixLength > maxUnderbarPrefixLength) {
      maxUnderbarPrefixLength = underbarPrefixLength;
    }
  }

  const arbitraryNamePrefix = `${'_'.repeat(maxUnderbarPrefixLength + 1)}arbitrary`;

  let namedExportCode = '';
  const defaultExportRows = [];
  const arbitraryNameExportRows: string[] = [];
  for (const [key, value] of Object.entries(data)) {
    if (key === makeLegalIdentifier(key)) {
      if (options.objectShorthand) defaultExportRows.push(key);
      else defaultExportRows.push(`${key}:${_}${key}`);
      namedExportCode += `export ${declarationType} ${key}${_}=${_}${serialize(
        value,
        options.compact ? null : t,
        ''
      )};${n}`;
    } else {
      defaultExportRows.push(
        `${stringify(key)}:${_}${serialize(value, options.compact ? null : t, '')}`
      );
      // A `default` key is exposed only through the default export object: a
      // `... as default` re-export would clash with the trailing `export default`
      // and produce a duplicate default export (a SyntaxError).
      if (key !== 'default') {
        // A valid `IdentifierName` that is not a legal binding identifier (a
        // reserved word or global, e.g. `switch`, `await`) is re-exported with the
        // unquoted `export { _x as switch }` form, valid since ES2015. Any other
        // key needs the quoted arbitrary-namespace form (ES2022+), which remains
        // opt-in via `includeArbitraryNames`.
        const isIdentifierName = identifierNameRE.test(key);
        if (isIdentifierName || (options.includeArbitraryNames && isWellFormedString(key))) {
          const variableName = `${arbitraryNamePrefix}${arbitraryNameExportRows.length}`;
          namedExportCode += `${declarationType} ${variableName}${_}=${_}${serialize(