Custom array merging

[TehShrike]

A potential fix for #14, #20, #21, #22, #24, #32.

The default merge strategy is exactly the same as it was before (though I'm suspicious of that falsey target property check on line 41 - that can be dealt with as a separate issue if need be).

You can implement whatever other array-merging strategy you like - the merge function is passed both arrays, plus the original options passed to deepmerge.

Any thoughts? Is this a good general solution? I didn't want to add complexity while solving this common issue.

I did a bit of refactoring in the first commit of this pull request, mostly to get rid of abbreviated variable names.

[KyleAMathews]

👍

[TehShrike]

I'll wait until the weekend to give any other contributors a chance to weigh in. If there aren't any other responses, I'll merge this and publish as a feature version bump, and close all the related pull requests and issues.

[macdja38]

this kinda destroys our ability to add an arbitrary number of arguments... #33

[TehShrike]

It keeps us from easily handling any number of arguments, but array merging behavior seems to be a much bigger deal for most users.

I think if there's enough user desire to pass in an arbitrary number of arguments, we can expose another method with a different API. Something like deepmerge.all([object1, object2, object3], optionsObject) perhaps. Assuming we agree that array merging is a higher priority, we can bikeshed #33 later.

[macdja38]

👍