iassign does not work correctly with ES6 Map

[martinbu]

Hi, thanks for this great helper library.

Does this library support ES6 Map? For me the following example does not work correctly. 'm' is always empty in the setProp and therefore map3 (or mapX) contains always one element after adding further elements.

import * as iassign from 'immutable-assign';

iassign.setOption({useConstructor: true});

let map1 = new Map();

  let map2 = iassign(
    map1,
    m => {
      m.set(0, 'first'); return m;
    }
  );

  let map3 = iassign(
    map2,
    m => { m.set(1, 'second'); return m; }
  );

  console.log(map1.size) // size: 0
  console.log(map2.size) // size: 1
  console.log(map3.size) // size: 1

Additionally, I have to set the useConstructor Option in every file (after import), that the option is applied correctly.

[engineforce]

ES6 Map support is added in 1.0.36, please refer to example 9.

Note: even with the fix, getProp() won't be able to handle navigate into the map object, it only supports navigate upto the map object. E.g.,

// Works
// Assume copyFunc option is set

var nested1 = { a: { b: new Map() } };
nested1.a.b.set("c", { "d": 100 })

var nested2 = iassign(
    nested1,
    (m, ctx) => m.a.b,
    (b) => {
        b.set(0, 'first'); return b;
    }
);

// Will not work
// Assume copyFunc option is set

var nested1 = { a: { b: new Map() } };
nested1.a.b.set("c", { "d": 100 })

var nested2 = iassign(
    nested1,
    (m, ctx) => m.a.b.get("c"),
    (c) => {
        c.e = 200; 
        return c;
    }
);

[engineforce]

Regarding to set the useConstructor Option in every file (after import), can you create a git repo that can reproduce the bug?