Return multiple values in JavaScript?

I am trying to return two values in JavaScript. Is this possible?

var newCodes = function() {  
    var dCodes = fg.codecsCodes.rs;
    var dCodes2 = fg.codecsCodes2.rs;
    return dCodes, dCodes2;
};

No, but you could return an array containing your values:

function getValues() {
    return [getFirstValue(), getSecondValue()]
}

Then you can access them like so:

const [first, second] = getValues()

This is called destructuring assignment and is supported by every major JS environment. It's equivalent to the following:

const values = getValues()
const first = values[0]
const second = values[1]

You can also return an object if you want to assign a name to each value:

function getValues() {
    return {
        first: getFirstValue(),
        second: getSecondValue(),
    }
}

And to access them:

const {first, second} = getValues()

Which is the same as:

const values = getValues()
const first = values.first
const second = values.second

It is highly recommended to return an object instead of an array unless the values make sense as a simple tuple, e.g. a coordinate pair [x, y]. With an array, it's easy to forget which value is which, it's harder to add more values later, and it's marginally more difficult to correctly type with TypeScript or JSDoc.