How To Deep Merge Instead Of Shallow Merge

When working with data structures in your code, merging objects is a common operation. You might be familiar with shallow merging, where properties from one object overwrite properties of another. However, in certain cases, you might need a more robust approach. That's where deep merging comes in handy.

Deep merging, also known as recursive merging, allows you to merge nested objects or arrays deeply, ensuring that all levels of the data structure are combined intelligently. This can be particularly useful when dealing with complex data or configurations that contain nested properties.

To deep merge two objects in JavaScript, you can make use of recursive functions to iterate through the properties of both objects and merge them appropriately at all levels. Here's a simple example implementation in JavaScript:

function deepMerge(target, source) {
    for (const key in source) {
        if (typeof source[key] === 'object' && source[key] !== null) {
            if (!target[key]) {
                target[key] = Array.isArray(source[key]) ? [] : {};
            }
            deepMerge(target[key], source[key]);
        } else {
            target[key] = source[key];
        }
    }
    return target;
}

const obj1 = {
    a: 1,
    b: {
        c: 2,
        d: 3,
    },
};

const obj2 = {
    b: {
        c: 4,
        e: 5,
    },
    f: 6,
};

const merged = deepMerge(obj1, obj2);
console.log(merged);

In this example, the `deepMerge` function takes two objects, `target` and `source`, and recursively merges them. If a property in `source` is an object itself, the function creates a corresponding object in `target` and calls itself recursively to merge the nested properties.

By using this deep merging approach, you can combine objects in a way that ensures all levels of the data are merged correctly. This can be especially beneficial when dealing with complex configurations or nested data structures that require a thorough merging process.

Keep in mind that deep merging may involve a bit more computational overhead compared to shallow merging, as it needs to traverse and merge all levels of the data structure. However, the trade-off is the capability to handle nested properties gracefully, providing a comprehensive merging solution for your JavaScript applications.

In conclusion, knowing how to deep merge instead of shallow merging can be a valuable skill when working with complex data structures in your code. By using recursive merging techniques, you can ensure that all levels of your objects are combined effectively, allowing for seamless integration of nested properties.