mixing camelcase and underscore code example

Example: underscore properties to camelcase

const keysToCamel = function (o) {
  if (isObject(o)) {
    const n = {};

    Object.keys(o)
      .forEach((k) => {
        n[toCamel(k)] = keysToCamel(o[k]);
      });

    return n;
  } else if (isArray(o)) {
    return o.map((i) => {
      return keysToCamel(i);
    });
  }

  return o;
};

  const toCamel = (s) => {
    return s.replace(/([-_][a-z])/ig, ($1) => {
      return $1.toUpperCase()
        .replace('-', '')
        .replace('_', '');
    });
  };

  const isArray = function (a) {
    return Array.isArray(a);
  };

  const isObject = (o) => {
    return o === Object(o) && !this.isArray(o) && typeof o !== 'function';
  };