Alternate way to detect changes to any value in an Object

proxy.js

let initialObject = {
    goingToChange: true,
    firstKey: 'firstKey',
    secondKey: 'secondKey',
    thirdKey: 'thirdKey'
};

const changedProperties = [];

// define a setter to push to an array if a value inside object changes
const handler = {
    set(target, property, value) {
        if (value != target[property]) {
            changedProperties.push(property);
        }
        target[property] = value;
        return true;
    },
    get: function (target, property) {
        return target[property];
    }
}

// assign the handler to the object via proxy
const proxyObject = new Proxy(initialObject, handler);

proxyObject.goingToChange = false;

// see the key present inside this array since value was changed
console.log(changedProperties);

// INFO: proxy can also prevent setting any other dataType to the key than the existing type
// proxies are awesome
// MORE reading at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy

alternatively, can use a Set to ensure O(1) complexity for lookups