Monaco Editor Component for Vue

Common errors

• Error: Monaco environment is not set up.

  cause The `monaco-editor-webpack-plugin` is either missing from the webpack configuration or incorrectly configured, preventing Monaco's global environment from being initialized.
  fix Ensure `monaco-editor-webpack-plugin` is installed (`npm install monaco-editor-webpack-plugin`) and correctly added to your `webpack.config.js` or `vue.config.js` `plugins` array, or `chainWebpack` configuration for Vue CLI.

• Error: Cannot find module 'monaco-editor-vue'

  cause The package `monaco-editor-vue` is not installed or the import path is incorrect.
  fix Run `npm install monaco-editor-vue` or `yarn add monaco-editor-vue` and verify the import statement `import MonacoEditor from 'monaco-editor-vue';` is correct.

• JavaScript heap out of memory

  cause Building a large application with Monaco Editor without proper optimization can consume excessive memory during the compilation process, especially if many languages and features are included without being tree-shaken.
  fix In your `monaco-editor-webpack-plugin` configuration, specify only the `languages` and `features` you absolutely need. Consider increasing Node.js's heap limit for your build script (e.g., `NODE_OPTIONS=--max_old_space_size=4096 vue-cli-service build`).

Warnings

• breaking The `monaco-editor-webpack-plugin` is a mandatory dependency for most setups and must be correctly configured in your build process (e.g., `webpack.config.js` or `vue.config.js` for Vue CLI). Omitting or misconfiguring it will lead to runtime errors or broken editor functionality, as Monaco Editor relies on its specific file loading mechanisms.
  Fix: Install `monaco-editor-webpack-plugin` and add it to your webpack configuration (or `chainWebpack` for Vue CLI). Ensure you list all required languages in its `languages` option to avoid bundling unnecessary editor features.
• gotcha Monaco Editor, and by extension `monaco-editor-vue`, only supports a single active theme at any given time. While you can change the theme dynamically via the `theme` prop, custom themes must be registered globally with the Monaco instance before the editor mounts. Direct programmatic manipulation of multiple themes simultaneously is not supported by Monaco itself.
  Fix: If you need to switch themes, dynamically update the `theme` prop. For custom themes, register them using the `monaco` instance provided by the `editorBeforeMount` event.
• gotcha The component supports both 'controlled' and 'uncontrolled' modes. If you bind a `value` prop, the component operates in controlled mode, requiring you to update the `value` prop yourself in response to `change` events. If no `value` prop is provided, it operates in uncontrolled mode, managing its own internal state. Mixing modes or not correctly handling `value` updates in controlled mode can lead to unexpected behavior.
  Fix: For controlled mode, always bind `value` and update it with the new value received from the `@change` event. For uncontrolled mode, omit the `value` prop and retrieve the editor content via its methods or the `change` event.
• gotcha Monaco Editor is a large library. Without proper tree-shaking and chunking through `monaco-editor-webpack-plugin`, it can significantly increase your application's bundle size, leading to slower load times. Importing all languages or features unnecessarily will exacerbate this problem.
  Fix: Configure `monaco-editor-webpack-plugin` to include only the `languages` and `features` your application strictly needs. Consider dynamic imports if the editor is not required on the initial page load.

Install

• npm install monaco-editor-vue npm
• yarn add monaco-editor-vue yarn
• pnpm add monaco-editor-vue pnpm

Imports

• MonacoEditor
  wrong:

  const MonacoEditor = require('monaco-editor-vue');

  correct:

  import MonacoEditor from 'monaco-editor-vue';

  Primary component import. Typically used within a Vue component's `components` option.
• MonacoWebpackPlugin
  wrong:

  const MonacoWebpackPlugin = require('monaco-editor-webpack-plugin');

  correct:

  import MonacoWebpackPlugin from 'monaco-editor-webpack-plugin';

  This is a critical Webpack plugin, not part of the `monaco-editor-vue` package directly, but required for correct setup.

Quickstart

This quickstart demonstrates how to set up `monaco-editor-vue` in a Vue 3 application with TypeScript, including the necessary Webpack configuration for the `monaco-editor-webpack-plugin`. It showcases basic usage with properties like `width`, `height`, `theme`, `language`, `options`, `value` (for controlled mode), and event handling for `change`, `editorBeforeMount`, and `editorMounted`.

<!-- vue.config.js for Vue CLI (or webpack.config.js for plain webpack) -->
const MonacoWebpackPlugin = require('monaco-editor-webpack-plugin');

module.exports = {
  chainWebpack: config => {
    config.plugin('monaco-editor').use(MonacoWebpackPlugin, [
      {
        languages: ['json', 'javascript', 'html', 'typescript', 'css']
      }
    ]);
  },
  // For older Vue CLI or plain webpack, ensure your publicPath is configured correctly if deploying to a sub-path
  // publicPath: process.env.NODE_ENV === 'production' ? '/my-app/' : '/' 
};

// src/App.vue
<template>
  <div id="app">
    <h1>Code Editor</h1>
    <MonacoEditor
      width="800"
      height="500"
      theme="vs-dark"
      language="javascript"
      :options="editorOptions"
      :value="code"
      @change="onChange"
      @editorBeforeMount="handleEditorBeforeMount"
      @editorMounted="handleEditorMounted"
    ></MonacoEditor>
  </div>
</template>

<script lang="ts">
import { defineComponent, ref } from 'vue';
import MonacoEditor from 'monaco-editor-vue';

export default defineComponent({
  name: 'App',
  components: {
    MonacoEditor
  },
  setup() {
    const code = ref('function hello() {\n  console.log("Hello Monaco Editor!");\n}');
    const editorOptions = ref({
      selectOnLineNumbers: true,
      minimap: { enabled: true },
      tabSize: 2
    });

    const onChange = (value: string) => {
      console.log('Editor value changed:', value);
      code.value = value; // Update model for controlled mode
    };

    const handleEditorBeforeMount = (monaco: any) => {
      // Optionally register custom themes or languages here
      console.log('Monaco editor before mount:', monaco);
    };

    const handleEditorMounted = (editor: any, monaco: any) => {
      console.log('Monaco editor mounted:', editor, monaco);
      // You can access the editor instance here to call its methods
    };

    return {
      code,
      editorOptions,
      onChange,
      handleEditorBeforeMount,
      handleEditorMounted
    };
  }
});
</script>

<style>
#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  margin-top: 60px;
}
</style>