Building a React Online Editor with Autocomplete

Introduction to React Online Editors

React is one of the most popular libraries for building user interfaces, especially for single-page applications. One of the exciting applications of React is creating online code editors that can be used for various purposes, such as learning programming languages, collaborating on code, or even just experimenting with code snippets. In this article, we will explore how to build a React online editor that includes autocomplete functionality, enhancing the development experience for users.

Autocomplete features can significantly improve productivity and reduce errors by providing developers with suggestions as they type. In a code editor, this is especially valuable, as it speeds up the coding process and helps less experienced developers learn syntax and available methods. By the end of this tutorial, you will have a working React online editor that offers suggestions for JavaScript code, complete with syntax highlighting and error handling.

We’ll dive into building our editor step by step, using modern React techniques. We will leverage libraries like CodeMirror for code editing capabilities and react-autosuggest or similar libraries for implementing the autocomplete functionality. Let’s get started!

Setting Up the Project

First things first, we need to create a new React application. You can do this by using the Create React App boilerplate, which sets up a robust development environment quickly.

npx create-react-app react-online-editor

After creating your project, move into the project directory:

cd react-online-editor

Next, let’s install the necessary libraries. We will be using CodeMirror for the code editor and react-autosuggest for implementing autocomplete:

npm install codemirror react-codemirror2 react-autosuggest

Once the installations are complete, your basic React application is ready, and we can start integrating our editor and autocomplete functionalities into it.

Integrating CodeMirror as Our Editor

CodeMirror is a versatile text editor implemented in JavaScript for the browser, which makes it perfect for our project. To get started with CodeMirror, we first need to import it into our React component.

Create a new file named Editor.js in the src directory and include the following code:

import React, { useState } from 'react';
import { Controlled as CodeMirror } from 'react-codemirror2';
import 'codemirror/lib/codemirror.css';
import 'codemirror/theme/material.css';
import 'codemirror/mode/javascript/javascript';

const Editor = () => {
  const [code, setCode] = useState('// Write your JavaScript code here');

  return (
     {
        setCode(value);
      }}
      onChange={(editor, data, value) => {}}
    />
  );
};

export default Editor;

If you were to render this Editor component in your App.js, you would be able to see a CodeMirror instance where users can write their JavaScript code.

Implementing Autocomplete Functionality

Now that we have a basic code editor set up, the next step is to add autocomplete features to assist users while they code. For this, we will leverage the react-autosuggest library, which provides a customizable autocomplete component.

Begin by creating a list of JavaScript keywords, built-in functions, and common methods that we can suggest to users as they type. Edit your Editor.js to incorporate react-autosuggest:

import React, { useState } from 'react';
import Autosuggest from 'react-autosuggest';

const suggestions = [
  'console',
  'document',
  'window',
  'setTimeout',
  'setInterval',
  'fetch',
  'Array',
  'String',
  'Math',
];

const Editor = () => {
  const [code, setCode] = useState('');
  const [value, setValue] = useState('');
  const [suggestions, setSuggestions] = useState([]);

  const onChange = (event, { newValue }) => {
    setValue(newValue);
  };

  const onSuggestionsFetchRequested = ({ value }) => {
    setSuggestions(getSuggestions(value));
  };

  const getSuggestions = (value) => {
    const inputValue = value.trim().toLowerCase();
    return suggestions.filter(suggestion =>
      suggestion.toLowerCase().slice(0, inputValue.length) === inputValue
    );
  };

  return (
    

       setSuggestions([])}
        getSuggestionValue={suggestion => suggestion}
        renderSuggestion={suggestion => 
{suggestion}
}
        inputProps={{
          placeholder: 'Type a JavaScript function...',
          value,
          onChange,
        }}
      />
       {
          setCode(value);
        }}
      />
    
  );
};

In this code, we’ve set up a basic list of suggestions and integrated Autosuggest into our component. As users type in the input field, matching suggestions will be displayed, allowing them to complete their code more efficiently.

Enhancing the Code Experience with Syntax Highlighting

A code editor wouldn’t be complete without syntax highlighting. While CodeMirror comes with built-in syntax highlighting, adding additional styling and themes can further enhance the user experience. You can choose from various themes provided by CodeMirror or create your own.

For our project, we will stick with the ‘material’ theme already imported. However, if you wish to customize your code editor further, you can define your styles in a CSS file and apply them to the CodeMirror wrapper components.

.editor {
  border: 1px solid #ccc;
  border-radius: 4px;
  height: 400px;
}

Incorporating these styles gives your editor a sleek and professional appearance, enhancing the overall user experience. Be sure to adjust or add styles as per your application’s requirement.

Testing and Debugging Your Editor

Once the online editor is built, testing is crucial to ensure everything works as expected. Use tools like Jest and Cypress for unit and end-to-end testing, respectively. Writing test cases for your editor involves simulating user inputs, ensuring suggestions appear correctly, and that selected suggestions fill the input as expected.

For example, you can write a simple Jest test case that checks if the suggestion list appears when typing into the input. Here’s how you might structure that:

test('suggestions appear when input field is typed into', () => {
  // simulate typing
  const suggestionsList = getSuggestions('console');
  expect(suggestionsList.length).toBeGreaterThan(0);
});

Conduct thorough testing to catch edge cases and ensure that your autocomplete and code editor features perform smoothly. Collect feedback from real users to identify areas for improvement.

Final Thoughts and Further Improvements

Congratulations! You have successfully built a React online code editor with autocomplete functionality. This serves as a fantastic base for a more sophisticated editor application. There are many avenues for enhancement, such as supporting multiple languages, persisting user sessions, or collaborating in real-time.

Consider expanding your editor with more advanced features, like additional keyboard shortcuts, linting for code quality checks, or even integrating with external APIs for fetching data. You could also implement a save feature that allows users to save their code snippets to local storage or a database.

Remember that the developer community thrives on sharing tools and resources. Consider making your editor open-source and encourage contributions from others. This way, you can continually improve your project and give back to the community!

Conclusion

Your journey into building a React online editor has equipped you with valuable skills and insights into modern web application development. We explored core concepts such as setting up a React project, integrating an editor, implementing autocomplete, and adding syntax highlighting.

With your new skills, you can create sophisticated web applications and tools that empower developers, foster collaboration, and make code learning easier for everyone. Keep experimenting with new ideas and technologies to continue growing as a developer. Happy coding!