alert time interval
using external underscore library
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
JavaScript
function alert_message_two () {
alert("hello");
}
function alert_message_one () {
alert("this first then waiting period");
_.delay(alert_message_two, 3000);
}
alert_message_one();
//using http://underscorejs.org/#delay in external resources