JSFiddle - React, Tailwind, and code Playground

JavaScript

function convertMinsToHrsMin(minutes) {
                var str = '';
       var h = Math.floor(minutes / 60) % 24;
       var m = minutes % 60;
                h = h < 10 ? '0' + h : h;
                m = m < 10 ? '0' + m : m;
                if (h >= 12) {
                    if (h == 12) {
                        str = "PM";
                    }
                    else if (h >= 22) {
                        h = (h - 12);
                        str = "PM";
                    }
                    else {
                        h = '0' + (h - 12);
                        str = "PM";
                    }
                }
                else {
                    if (h == 0) {
                        h = 12;
                        str = "AM";
                    }
                    else {
                        str = "AM";
                    }                     
                }                          
                return h + ":" + m + " " + str;
            }

            startTime = convertMinsToHrsMin(720);
            endTime = convertMinsToHrsMin(1080); 

            alert(startTime);
            alert(endTime);