lodash/internal/isKey.js

import isArray from '../lang/isArray';
import toObject from './toObject';

/** Used to match property names within property paths. */
var reIsDeepProp = /\.|\[(?:[^[\]]*|(["'])(?:(?!\1)[^\n\\]|\\.)*?\1)\]/,
    reIsPlainProp = /^\w*$/;

/**
 * Checks if `value` is a property name and not a property path.
 *
 * @private
 * @param {*} value The value to check.
 * @param {Object} [object] The object to query keys on.
 * @returns {boolean} Returns `true` if `value` is a property name, else `false`.
 */
function isKey(value, object) {
  var type = typeof value;
  if ((type == 'string' && reIsPlainProp.test(value)) || type == 'number') {
    return true;
  }
  if (isArray(value)) {
    return false;
  }
  var result = !reIsDeepProp.test(value);
  return result || (object != null && value in toObject(object));
}

export default isKey;