In Vue.js, when an error occurs in our application, an error page is usually displayed to the user. In this article, I will show you how to write error pages in Vue.js.

1. Create a vue component

First, you need to create a Vue component that will welcome your users. This component should include some information about the error that occurred, such as an error message or error code.

<template>
  <div class="error-page">
    <h1>Oops! Something went wrong.</h1>
    <h3>{{ errorMessage }}</h3>
    <p>Error code: {{ errorCode }}</p>
  </div>
</template>

<script>
export default {
  props: {
    errorMessage: {
      type: String,
      default: "An unknown error has occurred."
    },
    errorCode: {
      type: Number,
      default: 500
    }
  }
}
</script>

<style>
.error-page {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 100%;
  text-align: center;
}
</style>

In the above code, we define a Vue component named "Error Page". This component has two properties: errorMessage and errorCode. These properties provide the user with useful information about the error. If the user does not provide this information, the component will use default values.

This component displays an error message and an error code on the page.

2. Configuring Vue routing

Next, you need to configure Vue routing to navigate to the error page when an error occurs in your application.

Assume your application has the following file structure:

src/
  components/
    ErrorPage.vue
  views/
    Home.vue
    About.vue
  router.js
  App.vue
  main.js

To configure Vue routing, open the router.js file and add the following code to it:

import Vue from 'vue'
import Router from 'vue-router'
import Home from '@/views/Home.vue'
import About from '@/views/About.vue'
import ErrorPage from '@/components/ErrorPage.vue'

Vue.use(Router)

export default new Router({
  mode: 'history',
  routes: [
    { path: '/', name: 'home', component: Home },
    { path: '/about', name: 'about', component: About },
    { path: '/error', name: 'error', component: ErrorPage },
    { path: '*', redirect: '/error' }
  ]
})

In the above code, we define a new router instance. This instance has three paths: Home (/), About (/about), and Error (/error).

If the user navigates to an invalid path, we use redirects to redirect them to an error page.

3. Writing Vue.js Code

Now that we have configured the routing correctly, we can write some Vue.js code to navigate correctly when the application goes wrong.

First, open the App.vue file and add the following code to it:

<template>
  <div id="app">
    <router-view></router-view>
  </div>
</template>

<script>
export default {
  name: 'App',
  components: {},
  created() {
    // Error handling
    window.addEventListener('unhandledrejection', (event) => {
      this.$router.push({ name: 'error', params: { errorMessage: event.reason }})
    })
    window.addEventListener('error', (event) => {
      this.$router.push({ name: 'error', params: { errorMessage: event.error }})
    })
  },
}
</script>

In the above code, we have added two event listeners to the Vue root component.

The first listener is the unhandled rejection event, which is the event that occurs when a Promise is rejected and not handled.

The second listens for global errors, which are events that occur when unhandled JavaScript exceptions or other errors occur.

When these events occur, we use Vue routing to navigate the user to the error page, passing information about the error.

4. Testing

Now when an error occurs in your application, you will be automatically redirected to the error page and display the error message to the user.

You can test this feature by simulating an error. For example, you can open the console and type the following code:

Promise.reject('An error has occurred.')

When this code runs, it should redirect you to the error page with a message about the error.

Summary

In Vue.js, displaying error pages is an important task. In this article, we show you how to write error pages in Vue.js. By writing a Vue component, configuring Vue routing, and adding event listeners to the root Vue component, we can easily display information to the user about the errors that occurred.

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