Confusion over the "do...while" condition

I understand that if the conditional statement evaluates to false, nameCheck is reassigned to true. What I don't understand is how setting nameCheck to true exits the loop. Thus making the while condition evaluate to false.

Is this loop saying ... execute this loop as long as needed until nameCheck is "not false" or "true"?

Or is the evaluation of the condition more so this: (! + nameCheck). Meaning whatever the value of nameCheck is at the end of the loop, plug it into the condition. So if the conditional statement evaluates to false, nameCheck = true. Upon evaluation of the while, it reads (! + namecheck) ---> (! + true) ---> (false). Thus the loop ends.

Sorry about any confusion with regards to what I may be asking. I'm just looking for an explanation.

  var nameCheck = false;
  do {
    var accountName = prompt("Think of a name for your account");
    if (accountName === "") {
      alert("An account name is required for registration");
    } else {
      nameCheck = true;
    }
  } while (!nameCheck);