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21 - Destructuring Functions - Multiple returns and named defaults.md

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There's a couple of other things we can do with destructuring, and they all are related to functions. They're actually very handy.

Here's a convert currency function that takes an amount and returns an object that has U.S. dollars, British pounds, Australian dollars, and Mexican pesos.

function convertCurrency(amount) {
    const converted = {
        USD: amount * 0.76,
        GBP: amount * 0.53,
        AUD: amount * 1.01,
        MEX: amount * 13.30
    };
    return converted;
}

const hundo = convertCurrency(100);
console.log(hundo);

We run it here with $100 Canadian, and it's going to return an object, then when we console.log that object we'll see our values for each currency.

Previously, if I wanted to get the Australian dollars I would call for hundo.AUD in the console.log and hundo.MEX for pesos.

Destructure a function's returned value immediately

However with destructuring, you can sort of return multiple values from a function. You can't really return multiple values, but you can return an object and use destructuring to get your answer. Instead of using console.log(hundo), I'm going to destructure immediately as it comes back, and say USD, GBP, AUD, and MEX, and console.log them individually:

const { USD, GBP, AUD, MEX } = convertCurrency(100);
console.log(USD, GBP, AUD, MEX);

With that, you can use your console to return each currency individually, so we don't need that variable with all the individually properties for each currency on it. I can destructure them all into four separate values as needed.

Pick and Choose

Another cool thing about destructuring is that the order doesn't really matter because it's just an object, so I could put the currencies in any order that I would want and it would still work just fine. What's cool is that if you only need AUD and USD, you just don't use the currencies you don't need:

const { AUD, USD } = convertCurrency(100);

AUD and USD are returned for this function and then immediately destructured, and the other two will just be thrown out. However, you can still use console.log to show AUD and USD.

That's two things there: where you can return multiple values as well as pick and choose the pieces that you want returned from a function.