BUG: The Map type is not saved to a file about node-json-db

[stefnotch]

Yeah, for serializing a map, one would have to do something like this
https://stackoverflow.com/questions/29085197/how-do-you-json-stringify-an-es6-map/73155667#73155667

[Tijawk]

I think it's not a bug. A Map cannot be converted to JSON natively.

const map = new Map();
map.set('a', 1);
map.set('b', 2);
map.set('c', 3);

JSON.stringify(map) // return '{ }'

You should convert your map into object to save it.

Given in MDN, fromEntries() is available since Node v12:

const map1 = new Map([
['foo', 'bar'],
['baz', 42]
]);

const obj = Object.fromEntries(map1);
// { foo: 'bar', baz: 42 }
For converting object back to map:

const map2 = new Map(Object.entries(obj));
// Map(2) { 'foo' => 'bar', 'baz' => 42 }

source: https://stackoverflow.com/a/55537385