But in defence of JavaScript -- since it enjoys routine bashing, not always undeserved -- it now has true runtime-enforced private members (the syntax is prefixing the name with `#`, strictly as part of an ES6 class declaration), but yeah -- this doesn't invalidate the statement "kind of got there 32 years after Ada, stumbling over itself".
JavaScript has supported real data hiding since the beginning using closures. You define your object in a function. The function's local variables act as the private members of the object. They are accessible to all the methods but completely inaccessible to consumers of the object.
I completely forgot about closures. Frankly, they're still my go-to method for encapsulation, in part because the Java-isation of JavaScript done with the private class members and the onslaught of the "Alan Kay's ideas meet Simula" OOP flavour, is relatively new and I am still unsure whether it's a critical thing to have in JavaScript.
But in defence of JavaScript -- since it enjoys routine bashing, not always undeserved -- it now has true runtime-enforced private members (the syntax is prefixing the name with `#`, strictly as part of an ES6 class declaration), but yeah -- this doesn't invalidate the statement "kind of got there 32 years after Ada, stumbling over itself".