SOURCE

var fiber = {
    type: App
}

var isMount = true

var workInProcessHook

function Scheduler() {
    workInProcessHook = fiber.memoizedState
    isMount = false
    res = fiber.type()
}

function Dispatcher(queue, action) {
    var update = {
        action
    }
    if (queue.pending) {
        update.next = queue.pending.next
        queue.pending.next = update
    } else {
        update.next = update
    }
    queue.pending = update
    Scheduler()
}

function useState(initialValue) {
    var hook
    var baseState
    if (isMount) {
        hook = {
            memoizedState: initialValue,
            queue: {
                pending: null
            },
            next: null
        }
        if (!fiber.memoizedState) {
            fiber.memoizedState = hook
        } else {
            workInProcessHook.next = hook
        }
        workInProcessHook = hook
    } else {
        hook = workInProcessHook
        workInProcessHook = workInProcessHook.next
    }

    if (hook.queue.pending) {
        var first = hook.queue.pending.next
        var current = first
        var action
        do {
            action = current.action
            hook.memoizedState = typeof action === 'function' ? action(hook.memoizedState) : action
            current = current.next
        } while (current.next !== first)
        hook.queue.pending = null
    }

    return [hook.memoizedState, Dispatcher.bind(null, hook.queue)]
}

var input = document.getElementById('input')
var name = document.getElementById('name')
var btn = document.getElementById('button')
var btn2 = document.getElementById('button2')

function App() {
    const [count, setCount] = useState(0)
    const [nameValue, setName] = useState('name')
    const isFunc = Math.round(Math.random() * 10) % 2 === 0
    input.value = count
    name.value = nameValue
    return {
        onCountChange: () => setCount(isFunc ? (n) => n + 1 : Math.round(Math.random() * 100)),
        onNameChange: () => setName(Math.random())
    }
}




var res = App()

function onCountChange() {
    res.onCountChange()
}

function onNameChange() {
    res.onNameChange()
}

btn.addEventListener('click', onCountChange)

btn2.addEventListener('click', onNameChange)

<input id='input'/>
<input id='name'/><br/>
<button id='button'>change count</button>
<button id='button2'>change name</button>