The new ES6 JavaScript standard finally allows developers to declare variables using the handy const keyword. This prevents the value from being reassigned - somewhat reassuring if that’s a requirement.
That said, values declared with const can still be modified after the fact: they’re not immutable. If you’re after that particular bit of functionality, you can still fall back on the .freeze property that objects have access to. If you’re using strict mode - and why not? - you’ll receive a TypeError, unless you look to see whether the object .isFrozen.