feat: enable onload callbacks (#414)

* refactor(examples): run ssr example from server

* chore: switch to babel for build

buble complains too much

* feat: enable loaded callbacks

feat: add skip option

* examples: add async-callback browser example

* examples: fix server

* examples(ssr): add reactive script with callback

* fix: also skip on ssr

* chore: remove unused var

* feat: only add mutationobserver if DOM is still loading

feat: disconnect mutation observer once DOM has loaded

* examples: pass vmid to loadCallback instead of el

* feat: also support load callbacks for link/style tags

* test: add unit tests for load

* test: add load e2e test

* chore: fix lint

* chore: remove unused files

* test: fix e2e load callback test

* test: fix attempt

* examples: ie9 compatiblity

destructuring doesnt work in ie9

* fix: add onload attribute on ssr

dont rely on mutationobserver

* chore: lint ci conf

* refactor: remove loadCallbackAttribute config option

test: fix coverage for load

* test: improve coverage

* fix: only use console when it exists (for ie9)

* chore: fix coverage

examples/ssr/server.js

@@ -0,0 +1,27 @@
+import path from 'path'
+import fs from 'fs-extra'
+import template from 'lodash/template'
+import { createRenderer } from 'vue-server-renderer'
+import createApp from './App'
+
+const renderer = createRenderer({ runInNewContext: false })
+
+const templateFile = path.resolve(__dirname, 'app.template.html')
+const templateContent = fs.readFileSync(templateFile, { encoding: 'utf8' })
+
+// see: https://lodash.com/docs#template
+const compiled = template(templateContent, { interpolate: /{{([\s\S]+?)}}/g })
+
+process.server = true
+
+export async function renderPage () {
+  const app = await createApp()
+  const appHtml = await renderer.renderToString(app)
+
+  const pageHtml = compiled({
+    app: appHtml,
+    ...app.$meta().inject()
+  })
+
+  return pageHtml
+}