Negative index should not be used on arrays

This rule applies when a variable with negative value is used as an array index by wrong condition check.

When a variable is checked as negative, using it as an array index is not likely to be a programmer's intent.

-Noncompliant Code Example
+Compliant Code Example
 var arr = [1, 2, 3];
-if (x < 0) {
+if (x > 0) {
-    arr[x] = 3; // ARRAY_INDEX_NEGATIVE alarm: x is negative but is used as array index.
+    arr[x] = 3;
 }

Noncompliant Code Example

var arr = [1, 2, 3];
if (x < 0) {
    arr[x] = 3; // ARRAY_INDEX_NEGATIVE alarm: x is negative but is used as array index.
}

var arr = [1, 2, 3];
if (x > 0) {
    arr[x] = 3;
}