Cursor rule

1---
2alwaysApply: false
3---
4 
5## Use Loop for Min/Max Instead of Sort
6 
7Finding the smallest or largest element only requires a single pass through the array. Sorting is wasteful and slower.
8 
9**Incorrect (O(n log n) - sort to find latest):**
10 
11```typescript
12interface Project {
13  id: string
14  name: string
15  updatedAt: number
16}
17 
18function getLatestProject(projects: Project[]) {
19  const sorted = [...projects].sort((a, b) => b.updatedAt - a.updatedAt)
20  return sorted[0]
21}
22```
23 
24Sorts the entire array just to find the maximum value.
25 
26**Incorrect (O(n log n) - sort for oldest and newest):**
27 
28```typescript
29function getOldestAndNewest(projects: Project[]) {
30  const sorted = [...projects].sort((a, b) => a.updatedAt - b.updatedAt)
31  return { oldest: sorted[0], newest: sorted[sorted.length - 1] }
32}
33```
34 
35Still sorts unnecessarily when only min/max are needed.
36 
37**Correct (O(n) - single loop):**
38 
39```typescript
40function getLatestProject(projects: Project[]) {
41  if (projects.length === 0) return null
42  
43  let latest = projects[0]
44  
45  for (let i = 1; i < projects.length; i++) {
46    if (projects[i].updatedAt > latest.updatedAt) {
47      latest = projects[i]
48    }
49  }
50  
51  return latest
52}
53 
54function getOldestAndNewest(projects: Project[]) {
55  if (projects.length === 0) return { oldest: null, newest: null }
56  
57  let oldest = projects[0]
58  let newest = projects[0]
59  
60  for (let i = 1; i < projects.length; i++) {
61    if (projects[i].updatedAt < oldest.updatedAt) oldest = projects[i]
62    if (projects[i].updatedAt > newest.updatedAt) newest = projects[i]
63  }
64  
65  return { oldest, newest }
66}
67```
68 
69Single pass through the array, no copying, no sorting.
70 
71**Alternative (Math.min/Math.max for small arrays):**
72 
73```typescript
74const numbers = [5, 2, 8, 1, 9]
75const min = Math.min(...numbers)
76const max = Math.max(...numbers)
77```
78 
79This works for small arrays, but can be slower or just throw an error for very large arrays due to spread operator limitations. Maximal array length is approximately 124000 in Chrome 143 and 638000 in Safari 18; exact numbers may vary - see [the fiddle](https://jsfiddle.net/qw1jabsx/4/). Use the loop approach for reliability.
80