Question

I have some code to randomly highlight one name from a list (this works – see this fiddle):

function pickRandom() {
  var random = Math.floor(Math.random() * 6);
  $('.stname').css('background','none').eq(random).css('background','yellow');
}

But I’d like to make sure that the same names don’t come up over and over. So I intend to remember the last 3 chosen indexes as a blacklist:

var recentlyAsked = new Array();
function pickRandom() {
  var random;
  do {
    random = Math.floor(Math.random() * 6);
  } while ($.inArray(random,recentlyAsked));
  recentlyAsked.push(random);
  if (recentlyAsked.length >= 4) recentlyAsked.shift();
  $('.stname').css('background','none').eq(random).css('background','yellow');
}

This is not working; see this fiddle. Warning: it causes the browser to hang.

Any suggestions, please?

Answer 1

do {
    random = Math.floor(Math.random() * 6);
  } while ($.inArray(random,recentlyAsked));

Runs forever because inArray returns -1 when an item is not found in the array, which is a truthy value. 0 is the only number that is a falsy value. Your array is initially empty so nothing is found.

Fix it with :

do {
    random = Math.floor(Math.random() * 6);
  } while ($.inArray(random,recentlyAsked) > -1);

This will stop when it returns -1(not found)