gistfile1.js

const fun = ({param1 = 'some default value', param2 = 'other default value'} = {}) => {
  console.log(param1);
  console.log(param2);
  console.log(options); // Can I somehow get access to the object that has param1 and param2 inside?
  console.log(arguments[0]); // Is this the only way?
};

This is how I’d do it:

function fun(...args) {
    let [{param1 = 'some default value', param2 = 'other default value'} = {}] = args;
    console.log(param1);
    console.log(param2);
    console.log(args);
}

Done here this way: https://github.com/lmtm/node-pushpull/blob/master/src/pull.js

// access to options + simpler to read
(options = {}) => {
  // wanna know details ans defaults?
  // + access to individual params
  let {
    param1 = "...",
    param2 = "..."
  } = options;
}

Right, @naholyr’s code is the actual solution, I showed how to use a rest parameter instead of arguments.