Mircea Piturca commented on Behavioural Targeting - alerts based on length of time on page

var timeoutID;
var timeInMilliseconds = 2000;

function delayedAlert() {
  timeoutID = window.setTimeout(slowAlert, timeInMilliseconds);
}

function slowAlert() {
  // 2000 passed, do something here
}

This can be just a simple Javascript timeout call. You don't need an app for this.