Cursor rule

1---
2alwaysApply: false
3---
4 
5## Put Interaction Logic in Event Handlers
6 
7If a side effect is triggered by a specific user action (submit, click, drag), run it in that event handler. Do not model the action as state + effect; it makes effects re-run on unrelated changes and can duplicate the action.
8 
9**Incorrect (event modeled as state + effect):**
10 
11```tsx
12function Form() {
13  const [submitted, setSubmitted] = useState(false)
14  const theme = useContext(ThemeContext)
15 
16  useEffect(() => {
17    if (submitted) {
18      post('/api/register')
19      showToast('Registered', theme)
20    }
21  }, [submitted, theme])
22 
23  return <button onClick={() => setSubmitted(true)}>Submit</button>
24}
25```
26 
27**Correct (do it in the handler):**
28 
29```tsx
30function Form() {
31  const theme = useContext(ThemeContext)
32 
33  function handleSubmit() {
34    post('/api/register')
35    showToast('Registered', theme)
36  }
37 
38  return <button onClick={handleSubmit}>Submit</button>
39}
40```
41 
42Reference: [Should this code move to an event handler?](https://react.dev/learn/removing-effect-dependencies#should-this-code-move-to-an-event-handler)
43