org.sonar.l10n.javascript.rules.javascript.S888.html Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of javascript-checks Show documentation

There is a newer version: 10.20.0.29356

Why is this an issue?
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++) {
  // ...
}

Resources

   CWE - CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')