<script src="lib/Spec.js">
<script src="lib/UserAgent.js">
<script src="lib/DevToolsDetector.js">
<script>

    var spec = UserAgent(Spec());
    var lastState = null; // true is detected

    function _proceed() {
        DevToolsDetector(spec, function(err, yes) {
            var currentState = yes ? true : false;

            if (lastState !== currentState) {
                document.body.style.backgroundColor = currentState ? "yellow" : "blue";
                lastState = currentState;
            }
            setTimeout(_proceed, 2 * 1000);
        });
    }
    _proceed();

</script>