new Map() is broken

[loveencounterflow]

ES6 maps do not seem to work as described in https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map; specifically, var d = new Map(); d[ [ 1, 2, ] ] = 42; will cause a key '1,2' to be created, and allows to retrieve the value with d[ '1,2' ]. Moreover, d.forEach will not iterate, d.size will always be 0, d.has(...) always returns false, and both d.keys() and d.values() will always return an empty object {}, which is wrong on more than one level.

[Fishrock123]

@loveencounterflow Maps are not like arrays, you must use map.set(key, val) and map.get(key) to set/get values.

(This can be closed)

[Planeshifter]

To set a key, you should use the .set() method of the Map object, so you would use d.set( [ 1, 2, ]) = 42. Then everything works as expected.

[caitp]

this would be a v8 bug, not an iojs bug. That said, I don't believe this is valid.

d[ [1, 2] ] = 42 would behave like any object would, converting [1, 2] to a string (A.p.toString on arrays will be the same as array.join()), so you do get a key 1,2 with a value 42, just like you would with any object.

However, these object properties are not entries in the map, as far as the map is concerned (thus, doesn't show up in map entries/keys/values). it behaves the same (ish) as spidermonkey Map objects

[loveencounterflow]

ah i see. my bad, should've read the docs!

sadly, this also means that maps are no drop-in replacements for plain old objects. i tried the examples from the MDN site, everything seems ok (when using .get() and .set()).