How To Deeply Merge Two Object Values By Keys

So, you've found yourself in a situation where you need to merge two object values deeply by keys, huh? Don't worry, we've got you covered! In this article, we'll walk you through the process of merging two objects in JavaScript by matching keys and combining their values. Let's dive in!

To achieve a deep merge of two objects, we first need to understand the basic concept of object merging in JavaScript. When merging objects, we want to combine the properties of both objects in a way that results in a single object containing the combined key-value pairs.

One common approach to deep merging two objects is by using a recursive function. This function will iterate over all the keys in both objects and perform the merge operation for each key.

Here's a simple example to illustrate how you can achieve a deep merge of two objects:

function deepMergeObjects(obj1, obj2) {
    const merged = { ...obj1 };

    for (const key in obj2) {
        if (obj2.hasOwnProperty(key)) {
            if (typeof obj2[key] === 'object' && obj2[key] !== null) {
                if (typeof merged[key] === 'object' && merged[key] !== null) {
                    merged[key] = deepMergeObjects(merged[key], obj2[key]);
                } else {
                    merged[key] = { ...obj2[key] };
                }
            } else {
                merged[key] = obj2[key];
            }
        }
    }

    return merged;
}

const obj1 = {
    a: 1,
    b: {
        c: 2
    }
};

const obj2 = {
    b: {
        d: 3
    },
    e: 4
};

const mergedObj = deepMergeObjects(obj1, obj2);
console.log(mergedObj);

In this example, the `deepMergeObjects` function takes two objects (`obj1` and `obj2`) as arguments and recursively merges them into a new object `mergedObj`. The resulting object will contain the combined key-value pairs from both input objects.

By following this approach, you can effectively merge two objects deeply by matching keys and combining their values in a structured manner that maintains the integrity of the original objects.

Remember, understanding object merging in JavaScript can be a powerful tool in your coding arsenal, allowing you to manage and manipulate complex data structures with ease. So, the next time you find yourself needing to merge objects deeply by keys, just remember the simple yet effective technique we've discussed here!