DOMA-3719 Updated docstrings and other refactoring

Author: SavelevMatthew

apps/condo/domains/common/hooks/useCurrentBuild.tsx

@@ -6,16 +6,24 @@ const {
     publicRuntimeConfig: { serverUrl },
 } = getConfig()
 
-const REQUEST_KEY = '/api/version'
-const API_ROUTE = `${serverUrl}${REQUEST_KEY}`
+const REQUEST_CACHE_KEY = '/api/version'
+const FETCH_ROUTE = `${serverUrl}/api/version`
 
 async function fetchBuildInfo () {
-    const response = await fetch(API_ROUTE)
+    const response = await fetch(FETCH_ROUTE)
     return await response.json()
 }
 
+/**
+ * Fetch data about current build from a remote url using useSWR under the hood
+ * Which is similar to useQuery from "apollo-client"
+ * It has cache-validating mechanism:
+ * 1. Return value from cache by specified key
+ * 2. Fetch data from remote url and compare with cache value
+ * 3. Update return value if needed
+ */
 export function useCurrentBuild (): string {
-    const { data } = useSWR(REQUEST_KEY, fetchBuildInfo)
+    const { data } = useSWR(REQUEST_CACHE_KEY, fetchBuildInfo)
 
     return get(data, 'build', null)
 }

apps/condo/domains/common/hooks/useHotCodeReload.tsx

@@ -6,8 +6,10 @@ import { Button } from '@condo/domains/common/components/Button'
 import { useCurrentBuild } from './useCurrentBuild'
 import { usePrevious } from './usePrevious'
 
-
-
+/**
+ * Periodically fetch information about build and compare it with previous value
+ * If a change is found, a notification is shown to the user asking them to reload the tab
+ */
 export function useHotCodeReload (): void {
     const intl = useIntl()
     const NotificationTitle = intl.formatMessage({ id: 'HotCodeReload.title' })

apps/condo/domains/common/hooks/usePrevious.tsx

@@ -1,9 +1,12 @@
 import { useEffect, useRef } from 'react'
 
 /**
- * Monitoring some variable value
- * After it's change useEffect will update ref
- * But before that will be returned previous value
+ * Monitor some `variable` value
+ * Until `variable` is changed its previous value would be returned
+ * Changing the value of a variable will trigger an async ref change via useEffect
+ * At this point, the return value will still be the same
+ * This will catch the update state where value !== return value
+ * After useEffect has finished, the input and output value will be the same again
  * @param value to monitor
  */
 export function usePrevious<T> (value: T): T {