How can I use lodash's merge with a customizer?

Can you explain how to use lodash's merge function with a customizer?

Sure! Lodash's merge function combines objects, and a customizer allows you to define how values are merged.

What does the customizer function look like?

The customizer is a function that takes four arguments: objValue, srcValue, key, and object. You can return a value based on your merging logic.

Can you give me an example of a customizer in action?

Absolutely! Here's a simple example: if you want to concatenate arrays instead of replacing them, your customizer could look like this:

_.mergeWith(object1, object2, (objValue, srcValue) => {
  if (Array.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
});