JSFiddle - React, Tailwind, and code Playground

JavaScript

var times = {
    SaturdayClose: "21:00",
    SaturdayOpen: "10:00",
    SundayClose: "12:00",
    SundayOpen: "18:00",
    WeekdayOpen: "10:00",
    WeekdayClose: "21:00",
    WeekendOpen: "12:15",
    WeekendClose: "00:30"
};
    
console.log(times);

for (var time in times) {
    var parts = times[time].split(':'),
        hour = parts[0],
        minutes = parts[1];

    if (hour > 12) {
        times[time] = (hour - 12) + ':' + minutes + ' pm';
    } else if (hour == 0) {
        times[time] = 12 + ':' + minutes + ' am';
    } else if (hour == 12) {
        times[time] += ' pm';
    } else {
        times[time] += ' am';
    }
}

console.log(times);