Why does my React useEffect hook run multiple times even with an empty dependency array? [duplicate]

Question

I'm working on a React project and encountering an issue with the useEffect hook. My goal is to fetch data from an API only once when the component mounts. However, the useEffect seems to run multiple times, even though I've provided an empty dependency array.

Here’s my code snippet:

`

import React, { useEffect, useState } from "react";
import axios from "axios";

const MyComponent = () => {
    const [data, setData] = useState([]);

    useEffect(() => {
        console.log("Fetching data...");
        axios.get("https://jsonplaceholder.typicode.com/posts")
            .then(response => setData(response.data))
            .catch(error => console.error(error));
    }, []);

    return (
        <div>
            <h1>Data</h1>
            <ul>
                {data.map(item => (
                    <li key={item.id}>{item.title}</li>
                ))}
            </ul>
        </div>
    );
};

export default MyComponent;

`

I've verified that:

1. There are no other components or effects triggering this API call.
2. The issue persists even after restarting my development server.
3. My React version is 17.0.2.

My Question is :-

1. Why is this happening despite using an empty dependency array?
2. Could this be related to React's strict mode in development?
3. How can I ensure the useEffect runs only once as intended? Any insights or suggestions would be greatly appreciated!

Answer 1

Could this be related to React's strict mode in development?

Yes this is what happens when you have your App wrapped in <React.StrictMode>. Most likely in the Index.js

Here is a link explaining more : https://stackoverflow.com/a/61897567/15474532

How can I ensure the useEffect runs only once as intended? Any insights or suggestions would be greatly appreciated!

Remove strict mode. There are some reasons why you would want to keep it which you can read about here. https://react.dev/reference/react/StrictMode