prefer-array-every.md

Expected Behavior: prefer-array-every Rule

This rule enforces the use of Array.every() over manual for loops that return false when a condition is not met.

Examples

Basic Array Validation

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

Number Array Validation

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

Method Call Validation

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

Complex Condition Validation

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

Property Access Validation

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

Rule Scope

This rule only applies to:

• ✅ For loops that contain a return false statement
• ✅ For loops where the return false is inside an if statement
• ✅ For loops that return true at the end (indicating all items passed validation)

This rule does NOT apply to:

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

Auto-fix Behavior

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

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