> `const x = 2` feels great emotionally, but `const x = [2]` has the feeling of safety without any of the guarantee. Const is perfectly sensible with reference

> `const x = 2` feels great emotionally, but `const x = [2]` has the feeling of safety without any of the guarantee. Const is perfectly sensible with references to mutable objects too. The latter guarantees that x will always point to the same mutable array. If you pass a reference to the x array to a function which needs to mutate that specific array or observe it for changes, then it may be important that x is never rebound to a different array. Consider the following code: const x = [5,6,7]; Object.observe(x, function(changes) { console.log('changes', changes); }); // ... // time to clear the array // WRONG! The code observing changes to the old x array will not see // this change or future changes to this new array. Because we used const, this // will trigger an error and immediately show us our mistake. x = []; // CORRECT. This mutates the array instead of creating a new empty array. x.length = 0;