title: Thread-safe array deletions
body: <p>I know one can either <code>splice</code> an item out of an array, or delete it with <code>delete</code>. The former approach can cause concurrency problems, e.g. if one thread is walking over the array while another has just shifted or spliced. <code>delete</code> doesn't have this issue if <code>forEach</code> is used on the array, since <code>forEach</code> will walk over holes in the array.</p>
  
  <p>However, the array can't keep growing forever and will necessitate sweeping, potentially causing the same issue as in the case of a splice. Sounds like I need locking, but I'd be amused if Javascript had any facilities for it. Any thoughts?</p>