How do I format a timestamp in Javascript to display it in graphs? UTC is fine.

Question

Basically, I receive raw timestamps and I need to format them into HH:MM:SS format.

Answer 1

I'll go with the assumption that you mean Unix timestamps:

var formatTime = function(unixTimestamp) {
    var dt = new Date(unixTimestamp * 1000);

    var hours = dt.getHours();
    var minutes = dt.getMinutes();
    var seconds = dt.getSeconds();

    // the above dt.get...() functions return a single digit
    // so I prepend the zero here when needed
    if (hours < 10) 
     hours = '0' + hours;

    if (minutes < 10) 
     minutes = '0' + minutes;

    if (seconds < 10) 
     seconds = '0' + seconds;

    return hours + ":" + minutes + ":" + seconds;
}       

var formattedTime = formatTime(1266272460);
document.write(formattedTime);

Answer 2

This will display the current time in the format you asked for HH:MM:SS

function dostuff() { var item = new Date(); alert(item.toTimeString()); }

Answer 3

Here's a function that provides flexible formatting of a date in UTC. It accepts a format string similar to that of Java's SimpleDateFormat:

function formatDate(date, fmt) {
    function pad(value) {
        return (value.toString().length < 2) ? '0' + value : value;
    }
    return fmt.replace(/%([a-zA-Z])/g, function (_, fmtCode) {
        switch (fmtCode) {
        case 'Y':
            return date.getUTCFullYear();
        case 'M':
            return pad(date.getUTCMonth() + 1);
        case 'd':
            return pad(date.getUTCDate());
        case 'H':
            return pad(date.getUTCHours());
        case 'm':
            return pad(date.getUTCMinutes());
        case 's':
            return pad(date.getUTCSeconds());
        default:
            throw new Error('Unsupported format code: ' + fmtCode);
        }
    });
}

You could use it like this:

formatDate(new Date(timestamp), '%H:%m:%s');