Return formated date

dateFormat.ts

/**
 * parts
 * YYYY - 4 digits year
 * YY - 2 digits year
 * M - 1-12 month
 * MM - 01-12 month
 * D - 1-31 day
 * DD - 01-31 day
 * h - 1-23 hour
 * hh - 01-23 hour
 * p - 1-12 am/pm hour
 * pp - 01-12 am/pm hour
 * a - am/pm sign
 * m - 1-59 minutes
 * mm - 01-59 minutes
 * s - 1-59 seconds
 * ss - 01-59 seconds
 *
 * @param {Date} date
 * @param {string} input
 * @returns {string}
 */
function dateFormat(date: Date, input: string): string {
    const formats: { format: string, replacer: (d: Date) => string | number }[] = [
        {format: "YYYY", replacer: d => d.getFullYear()},
        {format: "YY", replacer: d => d.getFullYear().toString().substring(2)},
        {format: "MM", replacer: d => z(d.getMonth() + 1)},
        {format: "M", replacer: d => d.getMonth() + 1},
        {format: "DD", replacer: d => z(d.getDate())},
        {format: "D", replacer: d => d.getDate()},
        {format: "hh", replacer: d => z(d.getHours())},
        {format: "h", replacer: d => d.getHours()},
        {
            format: "pp",
            replacer: d => {
                const h = d.getHours();
                return z(h < 13 ? h : 24 - h);
            }
        },
        {
            format: "p",
            replacer: d => {
                const h = d.getHours();
                return h < 13 ? h : 24 - h;
            }
        },
        {format: "a", replacer: d => d.getHours() > 12 ? "pm" : "am"},
        {format: "mm", replacer: d => z(d.getMinutes())},
        {format: "m", replacer: d => d.getMinutes()},
        {format: "ss", replacer: d => z(d.getSeconds())},
        {format: "s", replacer: d => d.getSeconds()}
    ];

    let cursor = 0;
    let output = "";
    const strLen = input.length;
    while (cursor < strLen) {
        if (input[cursor] === "\\") {
            output += input.substr(cursor + 1, 1);
            cursor += 2;
            continue;
        }

        const matched = formats
            .filter(f => input.substring(cursor, cursor + f.format.length) === f.format)
            .sort((a, b) => b.format.length - a.format.length)
            [0];

        if (matched) {
            output += matched.replacer(date);
            cursor += matched.format.length;
        } else {
            output += input[cursor];
            cursor++;
        }
    }

    return output;
}

function z(n: number): string {
    return n < 10 ? `0${n}` : n.toString();
}