I Tested 5 AI Models on JavaScript Code Generation

JavaScript is different. Modern JS means React hooks, async/await, TypeScript, build tools. I tested all five models on real-world JavaScript tasks.

The Results

Ratings based on: proper hooks usage, TypeScript accuracy, error handling, cleanup, accessibility, and following 2025 best practices.

Real Task: Data Fetching Component

I asked each model to create a React component that fetches user data. Here's what they generated:

GPT-4o

// GPT-4o: React component with hooks
import React, { useState, useEffect } from 'react';

function UserProfile({ userId }) {
  const [user, setUser] = useState(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);

  useEffect(() => {
    async function fetchUser() {
      try {
        const response = await fetch(`/api/users/${userId}`);
        if (!response.ok) throw new Error('Failed to fetch');
        const data = await response.json();
        setUser(data);
      } catch (err) {
        setError(err.message);
      } finally {
        setLoading(false);
      }
    }

    fetchUser();
  }, [userId]);

  if (loading) return <div>Loading...</div>;
  if (error) return <div>Error: {error}</div>;
  if (!user) return null;

  return (
    <div className="profile">
      <h2>{user.name}</h2>
      <p>{user.email}</p>
    </div>
  );
}

export default UserProfile;

Works correctly. Missing cleanup on unmount, no TypeScript, no abort controller.

Claude 3.5 Sonnet

// Claude 3.5 Sonnet: React component with TypeScript
import React, { useState, useEffect } from 'react';

interface User {
  id: string;
  name: string;
  email: string;
}

interface UserProfileProps {
  userId: string;
}

interface FetchState {
  data: User | null;
  loading: boolean;
  error: Error | null;
}

const UserProfile: React.FC<UserProfileProps> = ({ userId }) => {
  const [state, setState] = useState<FetchState>({
    data: null,
    loading: true,
    error: null,
  });

  useEffect(() => {
    let isMounted = true;
    const abortController = new AbortController();

    async function fetchUser() {
      try {
        const response = await fetch(`/api/users/${userId}`, {
          signal: abortController.signal,
        });

        if (!response.ok) {
          throw new Error(`HTTP error! status: ${response.status}`);
        }

        const data: User = await response.json();

        if (isMounted) {
          setState({ data, loading: false, error: null });
        }
      } catch (err) {
        if (isMounted && err.name !== 'AbortError') {
          setState({
            data: null,
            loading: false,
            error: err instanceof Error ? err : new Error('Unknown error'),
          });
        }
      }
    }

    fetchUser();

    return () => {
      isMounted = false;
      abortController.abort();
    };
  }, [userId]);

  if (state.loading) {
    return <div className="loading" role="status">Loading...</div>;
  }

  if (state.error) {
    return <div className="error" role="alert">Error: {state.error.message}</div>;
  }

  if (!state.data) {
    return null;
  }

  return (
    <div className="profile">
      <h2>{state.data.name}</h2>
      <p>{state.data.email}</p>
    </div>
  );
};

export default UserProfile;

Full TypeScript, abort controller, cleanup, accessibility attributes. Production-ready.

DeepSeek Coder V2

// DeepSeek Coder: React with custom hook
import { useState, useEffect } from 'react';

function useFetch(url) {
  const [data, setData] = useState(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);

  useEffect(() => {
    const controller = new AbortController();

    fetch(url, { signal: controller.signal })
      .then(res => res.ok ? res.json() : Promise.reject(res))
      .then(data => {
        setData(data);
        setLoading(false);
      })
      .catch(err => {
        if (err.name !== 'AbortError') {
          setError(err);
          setLoading(false);
        }
      });

    return () => controller.abort();
  }, [url]);

  return { data, loading, error };
}

function UserProfile({ userId }) {
  const { data: user, loading, error } = useFetch(`/api/users/${userId}`);

  if (loading) return <div>Loading...</div>;
  if (error) return <div>Error: {error.message}</div>;
  if (!user) return null;

  return (
    <div className="profile">
      <h2>{user.name}</h2>
      <p>{user.email}</p>
    </div>
  );
}

export default UserProfile;

Extracted custom hook (good pattern), abort controller included, but no TypeScript.

The TypeScript Difference

When I asked for TypeScript specifically, the gap widened. Claude generated proper interfaces and type guards. GPT-4o added basic types. DeepSeek and Codestral often used 'any' or skipped types entirely.

Node.js and Express

I tested API endpoint creation. Here's a Node.js example from GPT-4o:

// Express API endpoint with validation
const express = require('express');
const router = express.Router();

// Simple validation middleware
const validateUser = (req, res, next) => {
  const { name, email } = req.body;

  if (!name || typeof name !== 'string' || name.trim().length === 0) {
    return res.status(400).json({ error: 'Valid name is required' });
  }

  if (!email || !email.match(/^[^\s@]+@[^\s@]+\.[^\s@]+$/)) {
    return res.status(400).json({ error: 'Valid email is required' });
  }

  next();
};

router.post('/users', validateUser, async (req, res) => {
  try {
    const { name, email } = req.body;

    // Simulate database call
    const user = {
      id: Date.now().toString(),
      name: name.trim(),
      email: email.toLowerCase(),
      createdAt: new Date().toISOString(),
    };

    res.status(201).json(user);
  } catch (error) {
    console.error('Error creating user:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

module.exports = router;

All models handle Express well. The differences show up in:

• Input validation (Claude uses Zod or custom validators, others use basic checks)
• Error handling (Claude always includes try/catch and proper status codes)
• Security (Claude mentions SQL injection, XSS without being asked)
• Async/await patterns (all models get this right)

React Hooks Gotchas

I tested each model on common React mistakes. Results:

My Recommendation

Use Claude 3.5 Sonnet for JavaScript and TypeScript.

The difference is larger in JavaScript than Python. Modern JS has too many footguns - cleanup, closures, async races, TypeScript complexity. Claude handles all of them correctly.

GPT-4o is acceptable for simple scripts and Node.js APIs. For React and TypeScript, the quality gap is significant.

When to Use Each

The Surprising Finding

DeepSeek extracted a custom hook without being asked. That's good architecture. But the hook had no TypeScript and no cleanup. It's like it understands patterns but not details.

Gemini 2.0 Flash is underrated for JavaScript. It's not quite Claude quality, but it's close on TypeScript and significantly cheaper.

Bottom Line

JavaScript moves fast. React 19, TypeScript 5.7, modern build tools. You need a model that keeps up.

Claude 3.5 Sonnet is the only model that consistently generates 2025-quality JavaScript. It uses proper cleanup, abort controllers, TypeScript, and accessibility attributes without being asked.

For Node.js backends where you're not using React hooks, GPT-4o is fine. For frontend work, spend the extra money on Claude.

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