Bare bones switch/case structure

function executeOperationsOnNumbers(op)
{
    var num;
    // - Begin switch
    switch(op)
    {
        // - Begin first case
        case "checkPrime":
            alert('Starting checkPrime case');
            alert('checkPrime case complete');
            break;
        // - End first case
        // - Begin second case
        case "checkPrime":
            alert('Starting findPrime case');
            alert('findPrime case complete');
            break;
        // - End second case
        // - Begin third case
        case "calcSum":
            alert('Starting calcSum case');
            alert('calcSum case complete');
            break;
        // - End third case
        // - Begin default
        default:
            alert('Starting default case');
            alert('default case complete');
            break;
    }
    // - End switch
}