JS计算距当前时间的时间差

/**
 * JS获取距当前时间差
 * 
 * @param int time JS毫秒时间戳
 *
 */
function get_time_diff(time) {
    var diff = '';
    var time_diff = new Date().getTime() - time;
    // 计算相差天数  
    var days = Math.floor(time_diff / (24 * 3600 * 1000));
    if (days > 0) {
        diff += days + '天';
    }
    // 计算相差小时数  
    var leave1 = time_diff % ( 24 * 3600 * 1000); 
    var hours = Math.floor(leave1 / (3600 * 1000));
    if (hours > 0) {
        diff += hours + '小时';
    } else {
        if (diff !== '') {
            diff += hours + '小时';
        }
    }
    // 计算相差分钟数  
    var leave2 =leave1 % (3600 * 1000);
    var minutes = Math.floor(leave2 / (60 * 1000));
    if (minutes > 0) {
        diff += minutes + '分';
    } else {
        if (diff !== '') {
            diff += minutes + '分';
        }
    }
    // 计算相差秒数  
    var leave3 = leave2%(60*1000);
    var seconds = Math.round(leave3/1000);
    if (seconds > 0) {
        diff += seconds + '秒';
    } else {
        if (diff !== '') {
            diff += seconds + '秒';
        }
    }
    
    return diff;
}