One important thing to note here is that this goes much further than `private` in TypeScript. The latter is purely a compile-time illusion. If you write `private x`, your objects' x property is still publically accessible and modifiable as far as the JS runtime is concerned. any other. It‘s just the TypeScript compiler that gives you an error if you access x, and only if it happens to have the type information it needs to do so (if the object ends up in an `any` variable, all bets are off).

This means TypeScript's "private" properties also shows up in the return value of Object.keys() etc. So it‘s a pretty leaky abstraction.

This proposal, on the other hand, tries to solve the much harder problem of of bringing true private instance variables to JS. This means making it impossible to access these variables from outside the project. To do this, they had to introduce a complete new "private namespace" that is different from the `this.<name>` one, because the latter is already reserved for the visible-to-everyone properties (messing with that would have serious compatibility implications). Hence the `#foo` syntax.