readme + event test improvements

Author: yyx990803

README.md

@@ -25,12 +25,42 @@ window.customElements.define('my-element', CustomElement)
 
 ### Props
 
+- All `props` declared in the Vue component are exposed on the custom element as its properties. Kebab-case props are converted to camelCase properties, similar to how they are converted in Vue.
+
+- Setting properties on the custom element updates the props passed to the inner Vue component.
+
+- Setting attributes on the custom element updates corresponding declared props. Attributes are mapped to kebab-case. For example, a prop named `someProp` will have a corresponding attribute named `some-prop`.
+
+- Attributes that map to props declared with `type: Boolean` are auto-casted into boolean values in the following rules:
+
+  - `""` or same value as attribute name: -> `true`
+
+  - `"true"` -> `true`
+
+  - `"false"` -> `false`
+
+- Attributes that map to props declared with `type: Number` are auto-casted into numbers if the value is a parsable number.
+
 ### Events
 
+Custom events emitted on the inner Vue component are dispatched on the custom element as a `CustomEvent`. Additional arguments passed to `$emit` will be exposed as an Array as `event.detail`.
+
 ### Slots
 
+Slots work the same way as expected, including named slots. They also update when changed (using `MutationObserver`).
+
+Scoped slots however, are not supported as they are a Vue specific concept.
+
 ### Lifecycle
 
+When the custom element is removed from the document, the Vue component behaves just as if it's inside a `<keep-alive>` and its `deactivated` hook will be called. When it's inserted again, the `activated` hook will be called.
+
+If you wish to destroy the inner component, you'd have to do that explicitly:
+
+``` js
+myElement.vueComponent.$destroy()
+```
+
 ## Acknowledgments
 
 Special thanks to the prior work by @karol-f in [vue-custom-element](https://github.com/karol-f/vue-custom-element).

test/fixtures/events.html

@@ -7,8 +7,9 @@
     </div>`
   }))
   window.el = document.querySelector('my-element')
-  el.addEventListener('foo', () => {
+  el.addEventListener('foo', e => {
     window.emitted = true
+    window.emittedDetail = e.detail
   })
   console.log('ready')
 })

test/test.js

@@ -95,6 +95,7 @@ test('events', async () => {
     el._shadowRoot.querySelector('button').click()
   })
   expect(await page.evaluate(() => window.emitted)).toBe(true)
+  expect(await page.evaluate(() => window.emittedDetail)).toEqual([123])
 })
 
 test('slots', async () => {