function getNamedArgs(args, opt_start) {
  opt_start = opt_start ? opt_start : 0;
  var obj = {};
  for (var i = opt_start, len = args.length; i < len; i += 2) {
    obj[args[i]] = args[i+1];
  }
  return obj;
}
function namedArgsFunc(x) {
  var args = getNamedArgs(arguments, 1);
  console.log('x ->', x);
  console.log('args ->', args);
}
> namedArgsFunc('x_variable', 'a', 1, 'b', 2)
x -> x_variable
args -> Object {a: 1, b: 2}