> The reference could be immutable but allow value reassignment, but is not the implementation of const.

You can reassign values through a const reference in javascript. For example:

    const x = [1]
    x[0] = 2 // ok!

This just doesn't work with primitive values, because primitive values are immutable and copy-by-value. So this works with lists but not strings (because strings are a primitive and thus immutable).

Or, put in C++ friendly terms, javascript doesn't distinguish between pointer reassignment and value reassignment. It only has reassignment, which is illegal for const variables. Variables which hold non-primitives (lists, objects, etc) are actually pointers to those values. const does not affect the mutability of the value stored at the pointer.