How can I deep merge two objects in JavaScript?

How can I deep merge two objects in JavaScript?

You can use the Object.assign() method or the spread operator, but for deep merging, a custom function is often needed.

Can you show me an example of a deep merge function?

Sure! Here's a simple deep merge function:

function deepMerge(target, source) {
    for (const key in source) {
        if (source[key] instanceof Object) {
            if (!target[key]) Object.assign(target, { [key]: {} });
            deepMerge(target[key], source[key]);
        } else {
            Object.assign(target, { [key]: source[key] });
        }
    }
    return target;
}

What if the objects have arrays? How does that work?

The function I provided will overwrite arrays. If you want to merge arrays instead, you'll need to modify the function to handle them specifically.