Add TypeScript example for event handling

src/guide/typescript-support.md

@@ -486,3 +486,36 @@ export default defineComponent({
   }
 })
 ```
+
+### Typing Event Handlers
+
+When dealing with native DOM events, it might be useful to type the argument we pass to the handler correctly. Let's take a look at this example:
+
+```vue
+<template>
+  <input type="text" @change="handleChange" />
+</template>
+
+<script lang="ts">
+import { defineComponent } from 'vue'
+
+export default defineComponent({
+  setup() {
+    // `evt` will be of type `any`
+    const handleChange = evt => {
+      console.log(evt.target.value) // TS will throw an error here
+    }
+
+    return { handleChange }
+  }
+})
+</script>
+```
+
+As you can see, without annotating the `evt` argument correctly, TypeScript will throw an error when we try to access the value of the `<input>` element. The solution is to cast the event target with a correct type:
+
+```ts
+const handleChange = (evt: Event) => {
+  console.log((evt.target as HTMLInputElement).value)
+}
+```