# compose

Ive been doing LaunchedEffect(list.size){ scrollToTop() } in order to scroll my LazyColumn to the top whenever the list size changes. This works great, but it also scrolls the list to the top whenever I navigate back to it since the LaunchedEffect is restarted. I could work around this with rememberSaveable, but that doesnt seem ideal. Is there another better approach?

Does the list instance change? If it doesn't change, you can use something like:

LaunchedEffect(list) {
    snapshotFlow { list.size }.drop(1).collect {
        scrollToTop()
    }
}

@Albert Chang I think the entire LaunchedEffect starts anew everytime the screen re-enters the composition (e.g. when navigating back to it).

That's why I'm using drop(1).

Ooooooh. Hmm, let me play around with it a bit! In the meantime, heres what I put together to solve it as well (your solution looks way better though).

@Composable
inline fun <T : Any> RememberEffect(
    value: T,
    crossinline action: suspend () -> Unit,
) {
    val scope = rememberCoroutineScope()

    rememberSaveable(value) {
        value.also {
            scope.launch { action() }
        }
    }
}

Yeah, that works too! 👍🏽 Im pretty sure its the better approach out of the two as well, theres really no need to save any values outside the composition!

Awesome, I really appreciate the help, thank you! 🙏🏽 Since Ill be using this in quite a few spots I put this together:

@Composable
fun <T> ScrollToTop(
    controller: ListController,
    key: T,
) {
    val updatedKey by rememberUpdatedState(key)

    LaunchedEffect(Unit) {
        snapshotFlow { updatedKey }
            .drop(1)
            .collect {
                controller.scrollToTop(
                    animated = true,
                )
            }
    }
}