Don't Show Again
Set the dontShowAgain option to true to display the "Don't Show Again" checkbox in your product tour.
This checkbox stores a cookie when it's clicked and next time the start() method is called, Intro.js first checks the cookie value and if it's not enabled, it runs the tour. Otherwise, Intro.js silently ignores the start() call.
// Check the dontShowAgain cookies first and then display the tour
introJs().setOption("dontShowAgain", true).start();