toUnderscore and toCamel functions

gistfile1.js

function toUnderscore(obj) {
  if (typeof obj !== 'object' || obj === null) {
    return obj;
  }
  if (Array.isArray(obj)) {
    return obj.forEach(toUnderscore);
  }
  Object.keys(obj).forEach(function (key) {
    if (/[a-z][A-Z]/.test(key)) {
      var k = key.replace(/([a-z])([A-Z])/g, '$1_$2').toLowerCase();
      obj[k] = obj[key];
      delete obj[key];
      key = k;
    }
    toUnderscore(obj[key]);
  });
  return obj;
}

function toCamel(obj) {
  if (typeof obj !== 'object' || obj === null) {
    return obj;
  }
  if (Array.isArray(obj)) {
    return obj.forEach(toCamel);
  }
  Object.keys(obj).forEach(function (key) {
    if (/[a-z]_[a-z]/.test(key)) {
      var k = key.replace(/([a-z])_([a-z])/g, function (_, $1, $2) {
        return $1 + $2.toUpperCase();
      });
      obj[k] = obj[key];
      delete obj[key];
      key = k;
    }
    toCamel(obj[key]);
  });
  return obj;
}

console.log(toUnderscore({
  fooBar: 1,
  fooBar2: 2,
  foo_bar3: 3
}));