App.vue
CompOne.vue
main.js
 
<template>
  <h1>The 'errorCaptured' Lifecycle Hook</h1>
  <p>Whenever there is an error in a child component, the errorCaptured() function is called on the parent.</p>
  <p>When the button inside the component is clicked, a method will run that tries to do changes to a $refs object that does not exist. This creates an error in the component that triggers the 'errorCaptured' lifecycle hook in the parent, and an alert box is displayed with information about the error.</p>
  <p>After clicking "Ok" in the alert box you can see the error in the browser console.</p>
  <div>
    <comp-one></comp-one>
  </div>
</template>

<script>
export default {
  errorCaptured() {
    alert("An error occurred");
  }
}
</script>

<style>
#app > div {
  border: dashed black 1px;
  border-radius: 10px;
  padding: 10px;
  margin-top: 10px;
  background-color: lightgreen;
}
</style>                  
<template>
    <h2>Component</h2>
    <p>This is the component</p>
    <button @click="generateError">Generate Error</button>
</template>

<script>
export default {
  methods: {
    generateError() {
      this.$refs.objEl.innerHTML = "hi";
    }
  }
}
</script>                  
import { createApp } from 'vue'

import App from './App.vue'
import CompOne from './components/CompOne.vue'

const app = createApp(App)
app.component('comp-one', CompOne)
app.mount('#app')
                  
http://localhost:5173/