{ "id": "c70a052196c35b5d0e09defd29577eed0824442da899bf53e83633566512987a", "pubkey": "38fe7b2b5215e40a79568920588b5886d6217a43570c28c0a32e36b1222e901e", "created_at": 1705783326, "kind": 31992, "tags": [ [ "d", "ba6a10ab-5dd7-4a87-801e-fd9abe243e49" ], [ "title", "Handling State Update on Unmounted Component in React" ], [ "L", "category" ], [ "l", "technical_and_precise", "category" ], [ "t", "react" ], [ "t", "javascript" ], [ "t", "async" ], [ "t", "web-dev" ], [ "a", "32019:38fe7b2b5215e40a79568920588b5886d6217a43570c28c0a32e36b1222e901e:ac852430-3bdd-4e5a-a71a-c928efa6aa27", "", "bae00740fafb00a79443b110e4ff1d754483c8cef5ca5480e684e5ba48ebd87f" ] ], "content": "I'm encountering a warning in my React application related to updating the state on an unmounted component. This typically happens when I navigate away from a page before an asynchronous operation (like fetching data from an API) is completed. Here's a simplified version of my component:\n\n```javascript\nimport React, { useState, useEffect } from 'react';\n\nconst MyComponent = () =\u003e {\n const [data, setData] = useState(null);\n\n useEffect(() =\u003e {\n const fetchData = async () =\u003e {\n const response = await fetch('/api/mydata');\n const result = await response.json();\n setData(result); // Warning occurs here if component unmounts before this line executes\n };\n\n fetchData();\n }, []);\n\n // Render logic...\n};\n\nexport default MyComponent;\n```\n\nI understand that the warning is due to the setData call occurring after the component has unmounted, but I'm unsure about the best way to handle this scenario in React. I've read about using a cleanup function in useEffect, but I'm not clear on how to implement it correctly in this context.\n\nCould anyone share insights or best practices on how to handle state updates on unmounted components in React, especially when dealing with asynchronous operations?", "sig": "36a0a572cc0402acbbf3173fc6e2f2b2fcef18b6eee213816f8fe6909f9be5c1c967aef798cc8efc46c3e15bfc3973df1ebe434544046b5fad9c26329b5e44c0" }