Uniqueness key for array comparison

[Halynsky]

The goal is to compare 2 arrays. As I see in the source, this library should be capable to do that. But there is an issue with key of elements. For example we have 2 arrays and we want to specify that uniqueness key is - id. But in the options we can specify only embeddedObjKeys. I am not sure that it's by design but I found such kind of workaround with empty key of embeddedObjKeys dictionary:

    console.log(diff(
      [
        {id: 1, name:"obj1"},
        {id: 2, name:"obj2"},
        {id: 3, name:"obj3"}
      ],
      [
        {id: 1, name:"obj1"},
        {id: 3, name:"objxxx"},
        {id: 4, name:"obj4"}
      ],
      {"": "id"}
    ))

But the issue is that it inner arrays becomes also be tracked by id. So this code will not give any changes.

    console.log(diff(
      [
        {id: 1, name:"obj1", children: [{name: "child1"}, {name: "child2"}]},
      ],
      [
        {id: 1, name:"obj1", children: [{name: "child2"}]},
      ],
      {"": "id"}
    ))

So if we add id for children. It works more correctly and show the changes. (But for example I have a case where children don't have an id)

    console.log(diff(
      [
        {id: 1, name:"obj1", children: [{id: 1, name: "child1"}, {id: 2, name: "child2"}]},
      ],
      [
        {id: 1, name:"obj1", children: [{id: 2, name: "child2"}]},
      ],
      {"": "id"}
    ))

Another option that also works is to specify children key. I think it kind of override. - {"": "id", "children": "name"}. But this is not very good for big and complicated objects with many child arrays.

Suggestions: Would be nice to have a way to specify just a key for array. And this key should be not used by child array. Way how it specified now is ok but at least need to be documented. Alternatives: {".": "id"} or {"$root": "id"}

[ltwlf]

In the version 1.2.6 of the software, all paths are treated as regular expressions, this was an issue. However, this approach has been revised in version 2 (ECMAScript Module). In consider for a future update to consider "" and "." to consider as root. Currently onlöy "" works as root.

In the context of how it's supposed to work, the notation {"": "id", "children": "name"} is correct. However, in version 1.2.6, the path children would be interpreted as /children/, matching any path containing the word "children". To precisely match the 'children' property of the root in version 1.2.6, it's recommended to use the regular expression ^children$.

Additionally, both versions allow the specification of a function to resolve the key for comparsion and name of the key, as detailed in the documentation of version 2. This functionality is also present in version 1.2.6.

[ltwlf]

Fixes in #108