JSFiddle - React, Tailwind, and code Playground

CSS

body { font-family: sans-serif; }

JavaScript

var timeString = "8:00:00";
var hourEnd = timeString.indexOf(":");
var H = +timeString.substr(0, hourEnd);
var h = H % 12 || 12;
var ampm = H < 12 ? "AM" : "PM";
timeString = h + timeString.substr(hourEnd, 3) + ampm;
document.write(timeString);