JSFiddle - React, Tailwind, and code Playground

JavaScript

function get_nth_suffix(date) {
    switch (date) {
    case 1:
    case 21:
    case 31:
        return 'st';
    case 2:
    case 22:
        return 'nd';
    case 3:
    case 23:
        return 'rd';
    default:
        return 'th';
    }
}

for (var i = 1; i < 32; ++i) {
    document.write(i + get_nth_suffix(i) + '<br>');
}