How to Write Your First JavaScript Function with AI Assistance in 2026

If you're a beginner looking to dive into JavaScript, you might feel overwhelmed by the sheer amount of information out there. The good news is that AI tools have come a long way in 2026, making it easier than ever to get started. In this guide, I'll show you how to write your first JavaScript function using AI assistance—all in about an hour.

Prerequisites

Before we jump in, here’s what you need:

• A computer with internet access
• A code editor (like Visual Studio Code, which is free)
• Basic understanding of programming concepts (variables, loops, etc.)
• An AI coding assistant (we’ll cover some options below)

Step 1: Choose Your AI Tool

There are several AI coding tools that can assist you in writing JavaScript functions. Here’s a quick comparison of some popular options:

| Tool Name | Pricing | Best For | Limitations | Our Take | |-------------------|------------------------------|-------------------------------|--------------------------------------|--------------------------------| | GitHub Copilot | $10/mo (free trial available) | Beginners and experienced devs | Can suggest incorrect code | We use this for quick suggestions. | | Tabnine | Free tier + $12/mo pro | Auto-completion and suggestions | Limited to JavaScript and few other languages | We don’t use it as much; Copilot is better for us. | | Codeium | Free | Free coding assistance | Limited features compared to others | We haven't tried it yet. | | OpenAI Codex | $20/mo | Advanced coding tasks | More complex than necessary for beginners | Not ideal for first-time users. | | Replit AI | Free tier + $15/mo pro | Collaborative coding | Requires internet connection | We use it for team projects. | | Sourcery | Free | Code review and suggestions | Focuses more on Python | We don’t use this for JavaScript. |

What We Actually Use

For beginners, I recommend starting with GitHub Copilot. It’s user-friendly and provides excellent support for writing JavaScript functions.

Step 2: Set Up Your Environment

1. Install Visual Studio Code: Download and install it from here.
2. Install GitHub Copilot: If you choose this tool, follow the instructions here.
3. Create a new JavaScript file: Open VS Code, create a new file, and save it as myFirstFunction.js.

Step 3: Write Your First Function

Now, let’s write a simple JavaScript function that adds two numbers together. Here’s how you can do it with the help of GitHub Copilot:

1. Start typing the function: Begin by typing function add(a, b) { and then press Enter.
2. Let Copilot suggest code: After the opening bracket, you can wait for Copilot to suggest the code. It often provides the complete function body.
3. Accept the suggestion: If the suggestion looks good, you can accept it by pressing Tab.

Your code should look something like this:

function add(a, b) {
    return a + b;
}

Expected Output

When you call add(2, 3), it should return 5.

Step 4: Test Your Function

1. Add test cases: Below your function, write some test cases like:

   console.log(add(2, 3)); // Output: 5
   console.log(add(-1, 1)); // Output: 0
   

2. Run your code: You can run your code in the terminal by typing node myFirstFunction.js.

Troubleshooting

• Error messages: If you see an error, double-check your syntax (missing brackets or semicolons are common issues).
• Function not returning what you expect: Make sure you’re passing the correct parameters.

Step 5: What's Next?

Now that you’ve written your first function, you can explore more complex concepts like:

• Function parameters and return types
• Arrow functions
• Higher-order functions

Consider building small projects to apply what you've learned, like a simple calculator or a to-do list app.

Conclusion

Getting started with JavaScript doesn’t have to be daunting, especially with AI tools like GitHub Copilot. By following these steps, you can write your first function in just about an hour.

Start here: Choose GitHub Copilot as your AI assistant, set up your environment, and dive into writing functions.