Cursor rule

1---
2alwaysApply: false
3---
4 
5## Do not wrap a simple expression with a primitive result type in useMemo
6 
7When an expression is simple (few logical or arithmetical operators) and has a primitive result type (boolean, number, string), do not wrap it in `useMemo`.
8Calling `useMemo` and comparing hook dependencies may consume more resources than the expression itself.
9 
10**Incorrect:**
11 
12```tsx
13function Header({ user, notifications }: Props) {
14  const isLoading = useMemo(() => {
15    return user.isLoading || notifications.isLoading
16  }, [user.isLoading, notifications.isLoading])
17 
18  if (isLoading) return <Skeleton />
19  // return some markup
20}
21```
22 
23**Correct:**
24 
25```tsx
26function Header({ user, notifications }: Props) {
27  const isLoading = user.isLoading || notifications.isLoading
28 
29  if (isLoading) return <Skeleton />
30  // return some markup
31}
32```
33