function preg_grep (pattern, input, flags) {
  // http://kevin.vanzonneveld.net
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // %          note 1: If pass pattern as string, must escape backslashes, even for single quotes
  // %          note 2: The regular expression itself must be expressed JavaScript style
  // %          note 3: It is not recommended to submit the pattern as a string, as we may implement
  // %          note 3:   parsing of PHP-style expressions (flags, etc.) in the future
  // *     example 1: var arr = [1, 4, 4.5, 3, 'a', 4.4];
  // *     example 1: preg_grep("/^(\\d+)?\\.\\d+$/", arr);
  // *     returns 1: {2: 4.5, 5: 4.4}

  var p = '',
    retObj = {};
  var invert = (flags === 1 || flags === 'PREG_GREP_INVERT'); // Todo: put flags as number and do bitwise checks (at least if other flags allowable); see pathinfo()

  if (typeof pattern === 'string') {
    pattern = eval(pattern);
  }

  if (invert) {
    for (p in input) {
      if (input[p].search(pattern) === -1) {
        retObj[p] = input[p];
      }
    }
  } else {
    for (p in input) {
      if (input[p].search(pattern) !== -1) {
        retObj[p] = input[p];
      }
    }
  }

  return retObj;
}

var arr = [1, 4, 4.5, 3, 'a', 4.4];
preg_grep("/^(\\d+)?\\.\\d+$/", arr);

{2: 4.5, 5: 4.4}