The Free Code Camp code runner has a built in Infinite Loop Protect feature, leveraged from JSBin's Loop Protect. The loop protect injects some code into user created loops to allow a safe exit if more than ~500ms has passed without exiting the loop. Loop protect will catch many, but not all infinite loop issues. If you see this message:

Error: Potential infinite loop at line X

It means you have been protected from an infinite loop.

Note: Loop Protect cannot detect infinite recursion.

In some cases - a slow computer or a long loop - you may get an incorrect loop protect. In order to disable loop protect, add the following comment over the line the loop protection message lists:

//noprotect

Warning: Disabling loop protect means you may potentially allow your code to go into an infinite loop, causing your browser to be unresponsive.

If you have erred and incorrectly disabled loop protection and now have an unresponsive solution, you can Disable Code Auto-Run.