I'd like to be able to specify restrictions on type usage in Javascript. For instance, in some cases I know that my array will always be 6 items larges - no sma

I'd like to be able to specify restrictions on type usage in Javascript. For instance, in some cases I know that my array will always be 6 items larges - no smaller, no larger, never sparse. But I can't specify this, yet it allows for certain optimizations (e.g. loop unrolling). Lately I was memory profiling an application in Javascript using Chrome. The fact that it used ES6 classes really helped, as some anonymous classes where hard to find memory leaks with, but the typed classes was a simple text query. I can imagine ES6 classes with decorators may enable specialized optimizations too.