JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/bacon.js/0.7.10/bacon.js"></script>
<div id="log"></div>

JavaScript

$(document).asEventStream('keypress')
    .filter(function (x) {
        return x.keyCode == 13;
    })
    .map(function () {
        return new Date().getTime();
    })
    .slidingWindow(2, 1)
    .map(function (x) {
        return (x.length == 1 || x[1] - x[0] > 5000) ? 1 : 2;
    })
    .onValue(function (x) {
        $("#log").text(x == 1 ? "Once" : "Twice in less than 5 secs");
    });