Hacky haxe plain javascript object with JS for/in key value loop.

HaxeJSObject.hx

package;

typedef Union2<T1,T2> = haxe.extern.EitherType<T1,T2>;

abstract JSObject( Dynamic ) from Dynamic to Dynamic
{
    public inline function new()
    {
        this = {};
    }
    
    @:arrayAccess
    public inline function get( key:Union2<String,Int> ):Dynamic
    {
      return untyped this[key];
    }
    
    @:arrayAccess
    public inline function set( key:Union2<String,Int>, value:Dynamic )
    {
        untyped this[key] = value;
    }
    
    public inline function forIn( body:String->Void )
    {
        untyped __js__( "for( var $k in {0} ) {1}", this, body(untyped $k) );
    }
        
    public inline function delete( key:Union2<String,Int> )
    {
        untyped __js__( "delete {0}[{1}]", this, key );
    }
}

See This comment for a nicer implementation for the for loop, with no need to defined your own var to hold the key.

@back2dos's implementation:

class Test {
    static function main() {
        var o = { x: 1 , y: 2 };
        forIn(o, function (s) {
            trace(s);
        });
    }
    static inline function forIn(target:Dynamic, body:String->Void) {
        untyped __js__( "for (let $k in {0} ) {1}", target, body(untyped $k) );
    }
}

Output:

(function () { "use strict";
var Test = function() { };
Test.main = function() {
	var o = { x : 1, y : 2};
	for (let $k in o ) console.log($k);
};
Test.main();
})();

Modified to reflect above method.