with immutable I mean that a value (value 1 and 2 in your example) can never change, you can reassign the variable to a new value though. If I understand the article correctly values in Rust and C++ can change eg. the memory location of the bits representing the value. Making it possible to shoot yourself in the foot if you don't know how the internals work, more so then in JavaScript as it's much more to keep track of. Even though it seems to be Rust's motto to limit such cases.
And I agree? that using const in JavaScript is like wearing a tin foil hat - it will rarely save you. If I have something that can change globally I make it upper case so it stands out and don't collide with other variables. And "use strict" should tell if you forgot to var(let/const) a variable. (unless there's a HTML id attribute with the same name) =)
Pointers point at bits of memory (its literally an address to a physical piece of memory or virtual memory allocated by something else - an OS for example) which store things like the 64bit floats '1' and '2' you are referring to in Javascript, and that is something someone writing C needs to think about pretty explicitly and is a source of errors. In Javascript you don't have to think about it very often in explicitly those terms as the runtime takes care of thinking about that for you.
You create all of these string, numbers, objects, etc... that the runtime has to keep track of for you using pointers, and once it thinks you are done with that memory it frees it up.
However, as I and other have said, while someone writing JavaScript doesn't have to think much about memory, you still have to think about references and values. Its also the case that the Garbage Collector isn't perfect, and sometimes as a JavaScript programmer you can accidentally create memory problems of your own:
