As you can see, one of the main differences between the old var and the new let/const declarations (besides their scope) is that the latter are constrained by the Temporal Dead Zone semantics, meaning they will throw a ReferenceError when accessed (read/write) before being initialized, instead of returning undefined as a var-declared variable would. This makes the code more predictable and easier to spot potential bugs. Simple, isn't it?

Your styles are scoped to the component. No more leakage, no more unpredictable cascade.

It's fashionable to dislike CSS. There are lots of reasons why that's the case, but it boils down to this: CSS is unpredictable. If you've never had the experience of tweaking a style rule and accidentally breaking some layout that you thought was completely unrelated — usually when you're trying to ship — then you're either new at this or you're a much better programmer than the rest of us.

Canonical publishes new releases of Ubuntu on a regular cadence, enabling the community, businesses and developers to plan their roadmaps with the certainty of access to newer open source upstream capabilities.