Table of Contents

• Motivation
• Installation
• Hooks
  • useIsMountedRef
  • useAbortController
• Migration from v1 to v2
• Component Lifecycle Overview
• Contributing
• Bugs and Sugestions
• License

Motivation

• Avoid memory leaks setting states when component are unmounted
• Automatically cancel fetch requests on unmount with AbortController
• Control when component is mounted
• Common error when setting state to unmounted component:

Warning: Can only update a mounted or mounting component. This usually means you called setState, replaceState, or forceUpdate on an unmounted component. This is a no-op.

Installation

yarn add use-is-mounted-ref
# or
npm install use-is-mounted-ref

Hooks

useIsMountedRef

Track component mount state with a ref.

Example: Avoid setState when unmounted

import { useState, useEffect } from 'react';
import { useIsMountedRef } from 'use-is-mounted-ref';

function App() {
  const isMountedRef = useIsMountedRef();
  const [state, setState] = useState({
    loading: true,
    error: false,
    data: [],
  });

  useEffect(() => {
    fetch('https://api.example.com/data')
      .then((response) => response.json())
      .then(({ data }) => {
        if (isMountedRef.current) {
          setState((prev) => ({ ...prev, loading: false, data }));
        }
      })
      .catch((err) => {
        if (isMountedRef.current) {
          setState((prev) => ({ ...prev, loading: false, error: true }));
        }
      });
  }, [isMountedRef]);

  return state.loading ? 'Loading...' : 'Found Data!';
}

useAbortController

Automatically abort fetch requests and async operations on unmount.

Example: Auto-cancel fetch on unmount

import { useState, useEffect } from 'react';
import { useAbortController } from 'use-is-mounted-ref';

function App() {
  const abortController = useAbortController();
  const [data, setData] = useState(null);

  useEffect(() => {
    fetch('https://api.example.com/data', {
      signal: abortController.signal,
    })
      .then((response) => response.json())
      .then(setData)
      .catch((err) => {
        if (err.name !== 'AbortError') {
          console.error(err);
        }
      });
  }, [abortController]);

  return <div>{data ? 'Loaded!' : 'Loading...'}</div>;
}

Example: Combine both hooks

import { useState, useEffect } from 'react';
import { useIsMountedRef, useAbortController } from 'use-is-mounted-ref';

function App() {
  const isMountedRef = useIsMountedRef();
  const abortController = useAbortController();
  const [state, setState] = useState({ loading: true, data: null });

  useEffect(() => {
    fetch('https://api.example.com/data', {
      signal: abortController.signal,
    })
      .then((res) => res.json())
      .then((data) => {
        if (isMountedRef.current) {
          setState({ loading: false, data });
        }
      })
      .catch((err) => {
        if (err.name !== 'AbortError' && isMountedRef.current) {
          setState({ loading: false, data: null });
        }
      });
  }, [abortController, isMountedRef]);

  return state.loading ? 'Loading...' : 'Loaded!';
}

Migration from v1 to v2

Breaking change: Default export replaced with named exports.

- import useIsMountedRef from 'use-is-mounted-ref';
+ import { useIsMountedRef } from 'use-is-mounted-ref';

New hook available:

import { useAbortController } from 'use-is-mounted-ref';

Component Lifecycle Overview

flowchart TD
    subgraph "Component Lifecycle"
        direction TB
        A1["Component Mounted"] --> A2["useIsMountedRef Hook"]
        A2 --> B1["useRef(false)"]
        B1 --> C1["useEffect Hook"]
        C1 --> D1["isMountedRef.current = true"]
        
        C1 --> E1["Component Unmounted"]
        E1 --> F1["Cleanup function"]
        F1 --> G1["isMountedRef.current = false"]
    end
    
    subgraph "Usage in Component"
        H1["Check if Component is Mounted"]
        H1 --> I1{isMountedRef.current ?}
        I1 -- "True" --> J1["Perform Mounted Actions"]
        I1 -- "False" --> K1["Do Not Perform Actions"]
    end

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

Bugs and Sugestions

Report bugs or do suggestions using the issues.

License

MIT License © helderberto