I sometimes write for-loops that do not have a block, but are just used for moving an index forward or searching through a chain.  For example:

    var container = field.parentNode;
    for (;container && container.className!='container';
         container = container.parentNode);
    // now do something with "container"

Netbeans incorrectly flags the semi-colon on the for-loop and reports that the code has no side effects, event though it does have the intended of setting the variable "container".