ES2015 Enhanced Object Literals

_sources.js

/// **Sources:**
/// * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer
/// * http://www.benmvp.com/learning-es6-enhanced-object-literals/
/// * http://2ality.com/2016/01/private-data-classes.html
/// * https://ariya.io/2013/02/es6-and-object-literal-property-value-shorthand

computedPropertyKeys.js

const NAME = "name",
      obj = {
          [NAME]: "John Smith" ///We're using a computed key here -- the end result will be that obj.name = John Smith.
      };
obj;

function namePlus(s) {
    return s + "name";
}
const anotherObj = {
    ["last" + "name"]: "Smith",
    [namePlus("first")]: "John"
};
anotherObj;

function createLogger() {
    const _el = Symbol("el"),
          el = document.createElement("div");
    el.style.whiteSpace = "pre-line";
    el.style.fontFamily = "monospace";
    
    return {
        [_el]: el, ///We can use "computed keys", too. Here we're faking a private property. These aren't _truly_ private, but "Object.keys", for example, can't see it. ("Reflect.ownKeys", though, can.)
        get el() {
            return this[_el];
        },
        write(...args) {
            this[_el].textContent += args.join(", ") + String.fromCharCode(13, 10);
        }
    }
}

const aDiv = createLogger();
aDiv.el;

aDiv.write("Hello, World!");
aDiv.write(".... more logging!", "... and even more!");

const propKeys = Object.keys(aDiv);
propKeys;

// you'll have to take my word here, Carbide doesn't like this, but ///This isn't the point of this playground, but as you can see here (if Carbide would let us), the symbol is not hidden from Reflect.ownKeys. If you run this in the JS console on browser that supports ES2015, this will render the output listed.
// it works in devtools.
// const ownKeys = Reflect.ownKeys(aDiv);
// ownKeys;
// ["el", "write", Symbol(el)] <-- NOT PRIVATE!

ES2015 Enhanced Object Literals.carbide.md

ES2015 Enhanced Object Literals

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mixAndMatch.js

function createGeolocationOptions({timeout = 30000, maximumAge = 30000, highAccuracy = true} = {}) {
    return {
        timeout,
        maximumAge,
        enableHighAccuracy: highAccuracy ///It's important to remember that we can mix and match as desired.
    };
}

const opts = createGeolocationOptions({timeout: 5000, highAccuracy: false});
opts;

point.js

const x = 10, y = 20,
      point = {x, y}; ///If our variable and the corresponding property key matches, we don't have to duplicate ourselves. ES5 would have required {x: x, y: y}.
po

shorthandFunctionDefinitions.js

const MATH = {
    add(a, b) { ///You can define functions _without_ the "function" keyword.
        return a + b;
    },
    sub: (a, b) => a - b, ///NOT arrow functions -- they're anonymous, so we have to provide a key.
    async theAnswer() { ///But we can use shorthand with Async functions...
        return 42;
    },
    * tenInts() { ///... and generators, too.
        for (let i = 0; i < 10; i++) {
            yield i;
        }
    }
}

const sum = MATH.add(2, 2);
sum;

const dif = MATH.sub(4, 2);
dif;

const theAnswer = await MATH.theAnswer();
theAnswer;

const tenInts = [...MATH.tenInts()];
tenInts;