<!-- BEGIN COPY / PASTE -->
        const array1 = [
            { id: 1, name: "Alice" },
            { id: 2, name: "Bob" }
        ];

        const array2 = [
            { id: 1, age: 25 },
            { id: 3, name: "Charlie" }
        ];

        const mergedArray = [...array1, ...array2].reduce((acc, obj) => {
            const existing = acc.find(item => item.id === obj.id);
            if (existing) {
                Object.assign(existing, obj);
            } else {
                acc.push(obj);
            }
            return acc;
        }, []);

        console.log(mergedArray);
        <!-- END COPY / PASTE -->