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A React hook that tells if the component is mounted.
import React from 'react'
export const useIsMounted = () => {
const ref = React.useRef(false)
const [, setIsMounted] = React.useState(false)
React.useEffect(() => {
ref.current = true
setIsMounted(true)
return () => (ref.current = false)
}, [])
return () => ref.current
}
@pharmpy-dev-123
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@timoxley I have since found ways to avoid having to use a useIsMounted hook, but from my rusty memory, the state is updated arbitrarily in the useEffect callback to trigger a re-render? I worked through a lot of gotchas to get it going.

The state update is in fact an instance of the forceUpdate pattern.

@tamvo22
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tamvo22 commented Oct 18, 2022

@zmeyc Thank you for the clarification! I tested with a delayed API calls and found that you are right. As you pointed out, it only reflected the initial mount status hook call. All this time, I was under the assumption that isMounted would return the useRef value at the time of the API request. When I pass the function isMounted() to call during the API return, it does provide the correct mounted value when my test component mounted and unmounted. Thanks again cheers!

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