JavaScript Relative Time

#javascript #typescript

I've found that Day.js and Moment.js's relative time support to be buggy, especially when dealing with very recent timestamps.

Here's an implementation in TypeScript:

// much love https://stackoverflow.com/questions/6108819/javascript-timestamp-to-relative-time

const units = {
    year: 24 * 60 * 60 * 1000 * 365,
    month: (24 * 60 * 60 * 1000 * 365) / 12,
    day: 24 * 60 * 60 * 1000,
    hour: 60 * 60 * 1000,
    minute: 60 * 1000,
    second: 1000
};

const rtf = new Intl.RelativeTimeFormat('en', { numeric: 'auto' });

export const getRelativeTime = (d1: Date, d2 = new Date()): string => {
    const elapsed = d1.getTime() - d2.getTime();

    // "Math.abs" accounts for both "past" & "future" scenarios
    for (const u in units) {
        if (Math.abs(elapsed) > units[u] || u == 'second') {
            return rtf.format(Math.round(elapsed / units[u]), u as Intl.RelativeTimeFormatUnit);
        }
    }
};

and raw JavaScript:

// much love https://stackoverflow.com/questions/6108819/javascript-timestamp-to-relative-time

const units = {
    year: 24 * 60 * 60 * 1000 * 365,
    month: (24 * 60 * 60 * 1000 * 365) / 12,
    day: 24 * 60 * 60 * 1000,
    hour: 60 * 60 * 1000,
    minute: 60 * 1000,
    second: 1000
};

const rtf = new Intl.RelativeTimeFormat('en', { numeric: 'auto' });

export const getRelativeTime = (d1, d2 = new Date()) => {
    const elapsed = d1.getTime() - d2.getTime();

    // "Math.abs" accounts for both "past" & "future" scenarios
    for (const u in units) {
        if (Math.abs(elapsed) > units[u] || u == 'second') {
            return rtf.format(Math.round(elapsed / units[u]), u as Intl.RelativeTimeFormatUnit);
        }
    }
};