Vue 2.6 unified scoped slots, named slots, and the default slot under a single `v-slot` directive, replacing what had grown into three slightly different syntaxes depending on when a given component was written. We went through our shared component library this month and updated everything to the new syntax, treating it as a small but worthwhile maintenance project rather than something to defer indefinitely just because the old syntaxes still technically worked.
Beyond just being tidier, it made a real difference for newer team members, who previously had to learn which of three slot syntaxes applied depending on the age of the component they were looking at — a genuinely confusing situation for anyone joining partway through the library's history, since nothing about a given component's file visually signaled which era's convention it happened to follow until you actually opened it and checked.
How we approached the migration itself
Rather than a single large rewrite, we updated components in small batches over about two weeks, running our existing test suite after each batch to catch any behavioral difference the syntax change might have introduced. The migration itself turned out to be almost entirely mechanical — the old and new syntaxes map onto each other predictably enough that we wrote a small find-and-replace script covering the most common patterns, handling only a handful of more unusual cases by hand.
One consistent pattern going forward is a small thing that nonetheless removes a recurring point of confusion in code review, where a reviewer previously had to mentally translate between syntaxes depending on which part of the codebase a given pull request touched. We have updated our internal component style guide to reflect only the new syntax going forward, and we plan to apply the same kind of periodic cleanup pass to other parts of our shared conventions whenever a future Vue release meaningfully simplifies something that has accumulated multiple generations of slightly different approaches over time.
A short training session that paid for itself
Beyond the mechanical migration, we ran a half-hour internal session walking through the new `v-slot` syntax and its shorthand `#` form, specifically for the couple of newer team members who had only ever known the old, fragmented syntaxes and had never had a reason to learn why they existed in three different forms in the first place. That short session removed more confusion than the migration itself did, since understanding why the old syntaxes existed at all turned out to matter more for confident day-to-day use than just knowing the new syntax's mechanical rules.
Destructuring scoped slot props, a small readability win
The unified syntax also made destructuring scoped slot props directly in the template noticeably cleaner than the old scoped-slot syntax allowed, letting a component consumer pull out exactly the named properties it needs from a slot's scope rather than binding the whole scope object under one name and then referencing properties off of it throughout the template. It is a small thing, but it showed up often enough across our shared component library that the cumulative readability improvement across dozens of call sites was more noticeable than we expected from what looked, on paper, like a fairly minor syntax convenience.
One thing that briefly broke during the migration
Our automated find-and-replace script mishandled one less common pattern — a component using a dynamically bound slot name — silently producing syntactically valid but behaviorally wrong output that only surfaced once a specific page relying on that component was manually tested. This was a useful reminder that a batch migration script covering the common cases still needs the same manual verification pass we would apply to any other refactor, rather than treating a script's clean run as proof the change is actually correct.