v7.0

[Justineo]

Major changes

⚠️ stands for breaking changes

• ⚠️ Drop support for Vue < 2.7 (no more npm install errors caused by @vue/composition-api as a peer dependency, fixes #576)
• ⚠️ Drop support for browsers without ResizeObserver (polyfill is required if you want to support older browsers)
• ⚠️ Remove UMD output
• Move to ESM (fixes #627, #782)

Checklist

• [x] Use ResizeObserver instead of the resize-detector package
• [x] Remove the extra wrapper and simplify styles
• [x] Move to `"type": "module"
• [x] Add pkg.exports
• [x] Update Rollup and plugins
• [ ] Update build scripts (WIP)

Blocker

types is now inferred by TypeScript itself and we are currently generating several copies of index.d.ts (as suggested by @xiaoxiangmoe), so we need to replacing their content during postinstall according to the Vue version. But for local development or CI/CD, we do not have index.vue{3,2}.d.ts the moment we run postinstall yet, which currently leads to deployment failures. (We used to just need to rewrite the pkg.types field to a different file name in postinstall.) So we need to find a way to fix this. Things to investigate:

• What issue will occur if we change to specifying types in pkg.exports?
• Can we just use the index.vue3.d.ts file generated in Vue 3 environment for Vue 2 projects so that we actually don't need to maintain a manually written index.vue2.d.ts file and the postinstall script?