map.delete(key) during map.forEach

Question

Typically, you cannot safely delete items from an list while you're looping through that list. Does this concept remain true for ES6 Maps?

I tried this simple test without exceptions:

var map = new Map([['a',1],['b',2],['c',3]]);
    map.forEach((value,key,map)=>
    {
          map.delete(key);
          let str = `["${key}",${value}] was deleted. `;
          str += `map.size = ${map.size}`;
          console.log(str);
    });

It seems ok.

Update: I just read this reference from Mozilla. It is certainly doable. I'd be interested in any performance benchmarks comparing this method of deletion with other methods (on larger datasets).

Answer 1

Well I guess you ar eright. I am not quite familiar with the ES6 Maps, but had done a bit of research and found this blog a bit helpful where it explains about the MAPS:

https://hackernoon.com/what-you-should-know-about-es6-maps-dc66af6b9a1e

Here you will get the deleting mechanism explanation too:
Something like this:

var m = new Map()
m.set('a', 1)
m.set('b', 2)
m.delete('a'); // true
m.delete('c'); // false (key was not there to delete)

Hope this helps.