jsdoc/packages/jsdoc-util/lib/cast.js

/**
 * Module to convert values between various JavaScript types.
 *
 * @alias module:@jsdoc/util.cast
 */

/**
 * Check whether a string contains a boolean or numeric value, and convert the string to the
 * appropriate type if necessary.
 *
 * @private
 * @param {string} str - The string to convert.
 * @return {(string|number|boolean)} The converted value.
 */
function castString(str) {
  let number;
  let result;

  switch (str) {
    case 'true':
      result = true;
      break;

    case 'false':
      result = false;
      break;

    case 'NaN':
      result = NaN;
      break;

    case 'null':
      result = null;
      break;

    case 'undefined':
      result = undefined;
      break;

    default:
      if (typeof str === 'string') {
        if (str.includes('.')) {
          number = parseFloat(str);
        } else {
          number = parseInt(str, 10);
        }

        if (String(number) === str && !isNaN(number)) {
          result = number;
        } else {
          result = str;
        }
      }
  }

  return result;
}

/**
 * Check whether a string represents another primitive type, and convert the string to the
 * appropriate type if necessary.
 *
 * If an object or array is passed to this method, the object or array's values are recursively
 * converted to the appropriate types. The original object or array is not modified.
 *
 * @private
 * @param {(string|Object|Array)} item - The item whose type or types will be converted.
 * @return {*?} The converted value.
 */
const cast = (module.exports = (item) => {
  let result;

  if (Array.isArray(item)) {
    result = [];
    for (let i = 0, l = item.length; i < l; i++) {
      result[i] = cast(item[i]);
    }
  } else if (typeof item === 'object' && item !== null) {
    result = {};
    Object.keys(item).forEach((prop) => {
      result[prop] = cast(item[prop]);
    });
  } else if (typeof item === 'string') {
    result = castString(item);
  } else {
    result = item;
  }

  return result;
});