I do not see that much of differences between Haxe and JS, mostly because Haxe is a superset of EcmaScript. However the process is not that automatic because TypeScript is more permissive I would say (though there is already a convertor from typescript to haxe: ts2hx).
But that said, I am not really that much experienced with TypeScript.
But that said, I am not really that much experienced with TypeScript.