Resolved Bug: Error: [Vue warn]: Unknown custom element: <my-component> – did you register the component

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  • “Resolved Bug: Error: [Vue warn]: Unknown custom element: – did you register the component correctly? Problem” ?
    • Summary
    • introduction
    • text
      • Looking for traces of bugs
        • What is `Unknown custom element`?
        • What is the source of the warning?
      • Bug dissection scene ♂?
        • Correct component registration
          • Global registration:
          • Partial registration:
        • Check the import path of the component
        • Handle asynchronous components
      • The magic of knitting solutions ?♂
        • Clarify the component registration scope
        • Using Webpack’s require.context()
        • Leveraging the ESLint plugin
      • How to avoid future bugs
        • Component naming convention
        • code review
        • automated test
    • Summarize
    • References
  • Original statement

《Resolved Bug: Error: [Vue warn]: Unknown custom element: – did you register the component correctly? Problem》 ?

Abstract

Meow, front-end friends, it’s another wonderful debugging time! Today, our group of nocturnal tigers will take you to solve a common bug in Vue.js – Unknown custom element: . Don’t let these errors clutter your elegant code. Follow me on a journey of discovery to easily solve this problem and learn how to avoid future front-end mistakes. Let’s start this code hunt!

Introduction

Vue.js is like a magic stone in front-end development, helping us build interactive user interfaces. However, even the most skilled owl wizard may make a small mistake when registering a component, resulting in an Unknown custom element warning. This warning is Vue telling us: “Meow, I don’t recognize this component you mentioned!” Don’t worry, we will solve it completely today.

Text

Looking for traces of bugs

What is Unknown custom element?

In Vue, this warning will appear when you try to use a component but Vue cannot find the corresponding definition.

What is the source of the warning?

This warning can be caused by several reasons:

  • The component was not registered correctly.
  • The component’s import path is wrong.
  • Due to asynchronous loading, the component is used before it is registered.

Bug anatomy scene ♂?

Correct component registration

Vue components need to be registered before use. This can be a global registration or a local registration.

Global registration:
Vue.component('my-component', {<!-- -->
  // ... options ...
})
Partial registration:
import MyComponent from './MyComponent.vue'

export default {<!-- -->
  components: {<!-- -->
    'my-component': MyComponent
  },
  // ... other options ...
}
Check the import path of the component
import MyComponent from './components/MyComponent.vue'

Make sure the path is correct and that the filename case matches the actual file, as some systems are case-sensitive.

Handling asynchronous components

If you are using asynchronous components, make sure they are loaded and resolved before use.

Vue.component('async-webpack-example', () => import('./my-async-component'))

The magic of weaving solutions ?♂

Clear component registration scope

Knowing when to use global registration and when to use local registration is important for maintaining a clear project structure.

Use Webpack’s require.context()

If you have a large number of components in your project, you can use Webpack’s require.context() to register all components globally.

const components = require.context('./components', true, /\.vue$/)

components.keys().forEach(fileName => {<!-- -->
  const componentConfig = components(fileName)
  const componentName = fileName.split('/').pop().replace(/\.\w + $/, '')

  Vue.component(componentName, componentConfig.default || componentConfig)
})
Using the ESLint plug-in

Use an ESLint plugin such as eslint-plugin-vue to detect potential registration errors.

How to avoid future bugs

Component naming convention

Follow a consistent naming convention, such as always using kebab-case to name component files.

Code review

Conduct a code review and have team members check if any component registrations are missing.

Automated testing

Write unit tests and end-to-end tests to ensure components load and render properly.

Summary

Solving the problem of Unknown custom element mainly revolves around correctly registering components and ensuring that they are used correctly. The cat head tiger blogger reminds you that carefulness is an essential skill for every good developer, especially when facing a magic framework like Vue. Check your registration process carefully and don’t let any bugs escape your eyes.

Reference materials

  1. Vue.js official documentation – component registration
  2. Webpack official documentation – require.context()
  3. ESLint-eslint-plugin-vue

Meow, I hope you have found and fixed the Unknown custom element problem. If you have other front-end questions, or want to share your Vue magic story, remember to leave your footprints in the comment area. See you next time as we continue our coding adventures! ?

Maotouhu recommends a list of necessary technology stacks for programmers:

Front-end technology Frontend:

  1. Basic Technology:

    • HTML5
    • CSS3 (and preprocessors such as Sass, Less)
    • JavaScript (ES6+)

  2. Front-end frameworks and libraries:

    • React
    • ? Angular
    • ?Vue.js
    • Svelte

  3. Status Management:

    • Redux (usually used with React)
    • MobX
    • ? NgRx (for Angular)
    • ?Vuex (for Vue)

  4. Tools and Build Systems:

    • ?Webpack
    • Rollup
    • Parcel
    • Babel (for JavaScript transpilation)

  5. Package Manager:

    • npm
    • Yarn

  6. Route management:

    • React-Router (for React)
    • ? Angular Router
    • ?Vue Router

  7. API and Communications:

    • Fetch API
    • Axios
    • GraphQL (and related clients like Apollo and Relay)

  8. Style and Component Library:

    • Styled Components
    • Ant Design
    • Bootstrap
    • ?Material-UI

  9. Test Tools:

    • Jest
    • Mocha
    • Cypress (for end-to-end testing)
    • Enzyme, Testing Library

  10. Version Control:

  • Git (and GitHub, GitLab, Bitbucket)
  1. Code Formatting and Quality Check:
  • ? ESLint
  • Prettier
  1. Performance Optimization and Monitoring:
  • ?Lighthouse
  • Web Vitals
  • Google Analytics
  1. Cross-platform mobile development:
  • React Native
  • ?Vue Native

Original Statement

======= ·

  • Original author: Maotouhu
  • Edit: Libin9iOak

Author wx: [libin9iOak]
Public account: Maotouhu technical team

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