updateCase

    <!-- begin SnapEngage code -->
<script type="text/javascript">
var uid;
var id;

  (function() {
    var se = document.createElement('script'); se.type = 'text/javascript'; se.async = true;
    se.src = '//storage.googleapis.com/code.snapengage.com/js/f53fc276-9ebe-4093-a1ac-3fcbf85a03c0.js';
    var done = false;
    se.onload = se.onreadystatechange = function() {
      if (!done&&(!this.readyState||this.readyState==='loaded'||this.readyState==='complete')) {
        done = true;
        /* Place your SnapEngage JS API code below */
        /* SnapEngage.allowChatSound(true); Example JS API: Enable sounds for Visitors. */
        
        SnapEngage.setCallback('ChatMessageReceived', function (agent, msg) {
            switch (agent) {
                case 'Kelsey':
                    uid = 11576622;
                    break;
                case 'Maricela':
                    uid = 14485590;
                case 'Alberto':
                    uid = 14485520;
                default:
                    uid = null;
        }
        // To update variables throughout the chat, use SnapEngage.updateCase("var1=val1,var2=val2");
        // the tricky thing is formatting that parameter value which might be beyond some people
        if (uid) {
            //id = uid; <-- this doesn't update the value of id
            SnapEngage.updateCase(id=uid);
            SnapEngage.updateCase("id="+uid);
        console.log(uid);
        console.log(id);
    }
    });
      }
    };
    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(se, s);
  })();
</script>
<!-- end SnapEngage code -->

You'll want to add a break; after each case statement, otherwise the logic will just fall through each time unless the agent is 'Kelsey'

Calling updateCase twice in a row like this may cause problems. Only the second call is necessary.

You'll also want to add another conditional to the if statement so that updateCase isn't called repeatedly. Something like this should work:

if (uid && id != uid) {
  id = uid;
  SnapEngage.updateCase("id");
}