How to Integrate ESLint Rules with @monaco-editor/react?

[restarajat]

Hi there,

I am currently using the @monaco-editor/react component in my React project to provide a code editor, and I want to add ESLint rules to lint the code as the user types. However, I am unsure how to configure ESLint to work with Monaco Editor in my React app.

What I have tried:
I installed eslint and configured a basic ESLint config (.eslintrc.js).
I tried integrating the eslint-plugin-monaco package, but I couldn't get it to show linting errors in the editor.
I've also tried manually setting up ESLint within Monaco’s API, but I'm unsure about how to make Monaco show the linting results.

My questions:
How can I configure @monaco-editor/react to use my custom ESLint rules?
Are there any packages or plugins that integrate ESLint with Monaco Editor for real-time linting support?
How can I display ESLint errors in the editor with Monaco?

Here’s an example of my current code for setting up Monaco:

`import React, { useRef } from 'react';
import Editor, { loader } from '@monaco-editor/react';
import * as monaco from 'monaco-editor';
import eslint from 'eslint';

loader.config({ monaco });

function CodeEditor() {
const editorRef = useRef(null);

// Initialize ESLint instance
const eslintInstance = new eslint.ESLint({
    baseConfig: {
        parser: '@typescript-eslint/parser', // Ensure using the TypeScript parser
        parserOptions: {
            ecmaVersion: 2020,
            sourceType: 'module',
            ecmaFeatures: {
                jsx: true,
            },
        },
        rules: {
            'no-console': 'warn', // Add your ESLint rules here
            // other rules...
        },
    },
    useEslintrc: false, // Disable external config loading for simplicity, or set to true to use .eslintrc
});

const onEditorMount = (editor, monaco) => {
    editorRef.current = editor;

    // Set up TypeScript support
    monaco.languages.typescript.typescriptDefaults.setDiagnosticsOptions({
        noSemanticValidation: false,
        noSyntaxValidation: false,
    });

    // Custom typings and suggestions for React Native
    monaco.languages.typescript.typescriptDefaults.addExtraLib(
        `declare module 'react-native' { export const View: any; /* add more as needed */ }`,
        'file:///node_modules/@types/react-native/index.d.ts'
    );

    // Lint the code whenever the model is created or changed
    const handleLinting = async (model) => {
        const code = model.getValue();

        try {
            const lintMessages = await eslintInstance.lintText(code, {
                filePath: model.uri.path,
            });

            // Convert ESLint results to Monaco markers
            const markers = lintMessages[0].messages.map((msg) => ({
                startLineNumber: msg.line,
                startColumn: msg.column,
                endLineNumber: msg.endLine || msg.line,
                endColumn: msg.endColumn || msg.column,
                message: msg.message,
                severity: monaco.MarkerSeverity.Error, // You can change severity based on the rule
            }));

            // Set markers in Monaco editor
            monaco.editor.setModelMarkers(model, 'eslint', markers);
        } catch (error) {
            console.error('Error during linting:', error);
        }
    };

    // Lint when the editor's model changes
    editor.onDidChangeModelContent(() => {
        const model = editor.getModel();
        if (model) {
            handleLinting(model);
        }
    });

    // Initial lint on model creation
    monaco.editor.onDidCreateModel((model) => {
        handleLinting(model);
    });
};

return (
    <Editor
        height="500px"
        defaultLanguage="typescript"
        defaultValue="// type your code here"
        onMount={onEditorMount}
        options={{
            automaticLayout: true,
            minimap: { enabled: false },
        }}
    />
);

}

export default CodeEditor;`