filterDeep review / refactoring

[YuriGor]

Same like in filterDeep we have cloneDeep option to let the user specify his own cloning method,
we need also to review all the deepdash methods where flat _.clone method used and also let user replace it.

[YuriGor]

Also check what's wrong with Lodash cloneDeep, as found by @GaborTorma in #56
It keeps deep function values instead of turning them into empty objects as per docs.

[YuriGor]

Opened yet another issue about this in Lodash

[YuriGor]

Currently, we have these issues with filterDeep:
it pretends to return a filtered clone of a given object, but the quality of this clone is far from one provided by Lodash's clone/cloneDeep.
filterDeep assumes the data consists of objects, arrays, and primitives.
we need to carefully handle such cases as

• class instances
• typed arrays
• maps and sets
• buffers and data views
• regexes
• functions
• read-only getters
• etc..
  all this great job already is done in Lodash, so the first step will be to properly use clone/cloneDeep.
• we need let Lodash clone regexes, maps, etc
• to avoid deep cloning of data under the childrenPath
• I have a LOT to learn from Lodash clone method.
  For example here is a small test how cone works:

console.clear();

class Test {
  constructor(x) {
    console.log('constructor',x); // called once
    if(!x)throw 'XXX!!!'; // no error, clone doesn't call it
    this.a = "a";
    this.b = "b";
    this.c = "c";
    this.x = x;
  }
  test(){
    console.log('test');
  }
  get z(){
    return 'z';
  }
}

const t = new Test('x');
t.d='d';
delete t.b;
t.hi = ()=>{console.log('hi')};
const tt = _.cloneDeep(t);

console.log(t); // Test {a: "a", c: "c", x: "x", d: "d"}
console.log(tt); // Test {a: "a", c: "c", x: "x", d: "d"}
t.test(); // works
tt.test(); // works
tt.hi(); // works, but I bieleve it's a Lodash's bug, according to docs tt.hi should by {} after cloning
console.log(t.test===tt.test); // equal because of this method comes from prototype
console.log(t.hi===tt.hi); // equal, but I bieleve it's a Lodash's bug, according to docs tt.hi should by {} after cloning
console.log(tt.z); // getters are functions in prototype, so it works

[muuvmuuv]

I would also like to add a new option to exclude the children from the output when it is empty. Example: https://codepen.io/yurigor/pen/GaKvNm?editors=0010 (parent 1.2 should not have children because it is empty)

[YuriGor]

you probably posted a wrong link - your example is just template without filtering done.
But the option you are asking about is already there - read about "keepIfEmpty" ones
https://deepdash.io/#filterdeep

[muuvmuuv]

Wow... I forgot to fork it, sorry. Yes, but only if I do not use childrenPath: https://codepen.io/muuvmuuv/pen/VweJLPe?editors=0011

[YuriGor]

Ok got it, will think about this.
It's not clear what to do if childrenPath is deep. not just next level property.
like here
if this option is true - then we need to remove only property by the last key of children's path, not the whole path.