JSFiddle - React, Tailwind, and code Playground

HTML

<div id="tapDiv" style="height:200px;width:200px;background-color:#000;color:#FFF"></div>

JavaScript

lastTapSeconds = 0;
        bpm = 0;

        var tapDiv = document.getElementById("tapDiv");

        function bpmCounter() { 

            var tapSeconds = new Date().getTime();

            bpm = ((1 / ((tapSeconds - lastTapSeconds) / 1000)) * 60);
            lastTapSeconds = tapSeconds;            
            tapDiv.innerHTML = Math.floor(bpm);  
        }

        tapDiv.onmousedown = bpmCounter;