prefer-array-some.md

Expected Behavior: prefer-array-some Rule

This rule enforces the use of Array.some() over manual for loops that return true when a condition is met.

Examples

Basic Array Search

  function hasActiveUsers(users) {
-   for (let i = 0; i < users.length; i++) {
-     if (users[i].isActive) {
-       return true
-     }
-   }
-   return false
+   return users.some(user => user.isActive)
  }

Number Array Search

  function hasPositiveNumbers(numbers) {
-   for (let i = 0; i < numbers.length; i++) {
-     if (numbers[i] > 0) {
-       return true
-     }
-   }
-   return false
+   return numbers.some(number => number > 0)
  }

Method Call Search

  function hasValidItems(items) {
-   for (let i = 0; i < items.length; i++) {
-     if (items[i].isValid()) {
-       return true
-     }
-   }
-   return false
+   return items.some(item => item.isValid())
  }

Complex Condition Search

  function hasComplexMatch(items) {
-   for (let i = 0; i < items.length; i++) {
-     if (items[i].active && items[i].value > threshold) {
-       return true
-     }
-   }
-   return false
+   return items.some(item => item.active && item.value > threshold)
  }

Property Access Search

  function hasActiveUsers(users) {
-   for (let i = 0; i < users.length; i++) {
-     if (users[i].profile.isActive) {
-       return true
-     }
-   }
-   return false
+   return users.some(user => user.profile.isActive)
  }

Rule Scope

This rule only applies to:

• ✅ For loops that contain a return true statement
• ✅ For loops where the return true is inside an if statement
• ✅ For loops that return false at the end (indicating no items matched)

This rule does NOT apply to:

• ❌ For loops that don't return true
• ❌ For loops that use break instead of return true
• ❌ For loops that return false in the middle (not at the end)
• ❌ For loops with side effects beyond searching
• ❌ For loops with multiple statements beyond searching
• ❌ Already using Array.some()

Auto-fix Behavior

The rule provides auto-fix suggestions that convert for loops to Array.some():

• for (let i = 0; i < arr.length; i++) { if (arr[i].isValid) { return true } } → arr.some(item => item.isValid)
• for (let i = 0; i < items.length; i++) { if (items[i].value > 0) { return true } } → items.some(item => item.value > 0)
• for (let i = 0; i < users.length; i++) { if (users[i].active) { return true } } → users.some(user => user.active)