var date = new Date(unix_timestamp*1000);
var hours = date.getHours();
var minutes = date.getMinutes();
var seconds = date.getSeconds();
// will display time in 21:00:00 format
var formattedTime = hours + ':' + minutes + ':' + seconds;

完整参考

getDate()   Returns the day of the month (from 1-31)
getDay()    Returns the day of the week (from 0-6)
getFullYear()   Returns the year (four digits)
getHours()  Returns the hour (from 0-23)
getMilliseconds()   Returns the milliseconds (from 0-999)
getMinutes()    Returns the minutes (from 0-59)
getMonth()  Returns the month (from 0-11)
getSeconds()    Returns the seconds (from 0-59)
getTime()   Returns the number of milliseconds since midnight Jan 1, 1970
getTimezoneOffset() Returns the time difference between GMT and local time, in minutes
getUTCDate()    Returns the day of the month, according to universal time (from 1-31)
getUTCDay() Returns the day of the week, according to universal time (from 0-6)
getUTCFullYear()    Returns the year, according to universal time (four digits)
getUTCHours()   Returns the hour, according to universal time (from 0-23)
getUTCMilliseconds()    Returns the milliseconds, according to universal time (from 0-999)
getUTCMinutes() Returns the minutes, according to universal time (from 0-59)
getUTCMonth()   Returns the month, according to universal time (from 0-11)
getUTCSeconds() Returns the seconds, according to universal time (from 0-59)
getYear()   Deprecated. Use the getFullYear() method instead