gistfile1.txt

macro (?.) {
    rule infix { $obj:ident | $prop:ident } => {
        ($obj && $obj.$prop ? $obj.$prop : undefined)
    }
    rule infix { $obj:expr | $prop:ident } => {
        ($obj && $obj.$prop ? $obj.$prop : undefined)
    }
}


var o = { foo: { bar: 42} };
console.log(o?.foo?.bar)