Testing for loop termination using an equality operator (== and !=) is dangerous, because it could set up an
infinite loop. Using a broader relational operator instead casts a wider net, and makes it harder (but not impossible) to accidentally write an
infinite loop.
Noncompliant code example
for (var i = 1; i != 10; i += 2) // Noncompliant. Infinite; i goes from 9 straight to 11.
{
//...
}
Compliant solution
for (var i = 1; i <= 10; i += 2) // Compliant
{
//...
}
Exceptions
Equality operators are ignored if the loop counter is not modified within the body of the loop and either:
- starts below the ending value and is incremented by 1 on each iteration.
- starts above the ending value and is decremented by 1 on each iteration.
Equality operators are also ignored when the test is against null.
for (var i = 0; arr[i] != null; i++) {
// ...
}
for (var i = 0; (item = arr[i]) != null; i++) {
// ...
}
