Typescript breaking changes in minor version bump

[ajeffrey]

hey, I've just spent the past 5 hours hunting down an issue where running npm install caused my typescript-based build to fail at runtime with Vue.use is not a function. I just re-checked the typescript integration page and it seems that the build system has been intentionally broken for typescript in a minor version bump, meaning that npm's default caret version matcher moved me onto 2.2.0 and invisibly broke my build. I've had to look through every build-related package I run, reverting to previous versions to figure out what went wrong.

I really appreciate all the hard work you guys are putting into making Vue, but can you please try to avoid breaking published compatibility guidelines in minor version increments? I understand that you're wanting to move into ESM-based modules but simply updating the .d.ts files in line with this change would prevent breaking people's dependencies silently.

[yyx990803]

Sorry, this was unintentional. We surely don't want to break your stuff on minor releases. The incompatibility is a result of the combination of TypeScript + webpack 2, which unfortunately was not covered in our typings tests because the tests didn't take the interaction with webpack 2 into account.

However, even if we changed the d.ts to use ES-style exports, it would still be a breaking change, because AFAIK ES-style exports can't be made to work with existing CommonJS imports (import Vue = require('vue')).

Since the change is already out there, we will likely take the opportunity to fully migrate to ES-based exports in all our typings (See #5016). That said, we do apologize for the unintended breaking changes.

P.S. the workaround for now is simply configure webpack to alias vue to use the CommonJS build (vue/dist/vue[.runtime].common.js).

Update: we now recommend using allowSyntheticDefaultImports with ES style imports. See updated TS setup docs for more details.

[ajeffrey]

don't sweat it - it happens. I think changing the d.ts files would help, if only because the issue would become a compilation rather than a runtime error, and therefore provide a more relevant error message. As it was, I ended up looking through all my build modules (webpack, ts-loader, vue-loader etc) thinking that something had stopped performing esm-cjs interop.

Thanks for getting back to me though, and thanks for the hard work you put in making Vue really great.

[yyx990803]

Update: we now recommend using allowSyntheticDefaultImports with ES style imports. See updated TS setup docs for more details.

[ajeffrey]

great, thanks! I'll check it out.