js 获取网络时间:

由于new Date获取的是客户本地时间，有些情况下我们需要获取网络时间，避免用户更改本地时间而产生的某些功能冲突，则我们可以通过如下方法从浏览器获取我们服务器上的时间！ 你也可以获取不同网址上的时间，如：www.baidu.com

const request = new XMLHttpRequest();
request.open("GET", "/", true);  // 中间参数可以改成  www.baidu.com
request.send();
//该属性每次变化时会触发
request.onreadystatechange = function(){
    if(request.readyState === 4 && request.status === 200){
        console.log(request.getResponseHeader("Date"))              //请求服务器的响应时间
        console.log(Date.parse(request.getResponseHeader("Date")))  //获取到的时间戳
    }
}

同步获取：（封装获取网络时间方法）

方法一：

axios 获取服务器时间 response.header.date

扩展：（axios 请求头缺失date的原因）
需要服务端设置字段： Access-Control-Expose-Headers
https://github.com/axios/axios/issues/606
https://stackoverflow.com/questions/37897523/axios-get-access-to-response-header-fields

没有设置请求头缺失 如下:

// 
{
    content-type: "application/json; charset=utf-8",
    cache-control: "max-age=0, private, must-revalidate"
}

方法二：

// 封装同步获取获取网络时间方法
function getServerTime(){
 return new Promise((resolve) => {
   const request = new XMLHttpRequest()
    request.open("GET", "/", true)
    request.send()
    request.onreadystatechange = function(){
    	const serverTime = request.getResponseHeader("Date")
          if (serverTime) {
            resolve(Date.parse(serverTime))
          } else {
            resolve(new Date().valueOf())  //没网情况获取本地时间
        }
    }
 })
}

//使用
getServerTime().then((time) => {
console.log(time)
})

requests.get(url=url).elapsed.total_seconds()   #时间为秒

可以获取从发起请求到服务器响应的时间

如，延时响应一秒，获取服务器响应时间

延时响应3秒，获取服务器响应时间

有时候为了测试网络情况，需要返回每个阶段的耗时时间，比如DNS解析耗时，建立连接所消耗的时间，从建立连接到准备传输所使用的时间，从建立连接到传输开始所使用的时间，整个过程耗时，下载的数据量，下载速度，上传数据量，上传速度等等

有时候为了测试网络情况，需要返回每个阶段的耗时时间，比如DNS解析耗时，建立连接所消耗的时间，从建立连接到准备传输所使用的时间，从建立连接到传输开始所使用的时间，整个过程耗时，下载的数据量，下载速度，上传数据量，上传速度等等。下面的脚本获取以上信息：

CURL的资料参见： http://curl.haxx.se/libcurl/c/curl_easy_getinfo.html

复制代码 代码如下:

###################################
### author: www.ttlsa.com   ###
### QQ群: 39514058     ###
### E-mail: service@ttlsa.com  ###
###################################
use strict;
use Data::Dumper;
use WWW::Curl::Easy;

if(!@ARGV){
 print "Usaging: $0 url\n";
 print "For example: $0 www.ttlsa.com\n";
 exit;
}

my $curl = new WWW::Curl::Easy;
open my $response_body,">/dev/null";
$curl->setopt(CURLOPT_HEADER,1);
$curl->setopt(CURLOPT_URL, $ARGV[0]);
$curl->setopt(CURLOPT_WRITEDATA,\$response_body);
$curl->perform;
my $err = $curl->errbuf;
if(!$err){
 my $st = &getTime;
 my $http_code = $curl->getinfo(CURLINFO_RESPONSE_CODE);
 my $http_dns_time = $curl->getinfo(CURLINFO_NAMELOOKUP_TIME);
 my $http_conn_time = $curl->getinfo(CURLINFO_CONNECT_TIME);
 #my $http_APP_time = $curl->getinfo(CURLINFO_APPCONNECT_TIME);
 my $http_PRE_TRAN_time = $curl->getinfo(CURLINFO_PRETRANSFER_TIME);
 my $http_START_TRAN_time = $curl->getinfo(CURLINFO_STARTTRANSFER_TIME);
 my $http_TOTAL_time = $curl->getinfo(CURLINFO_TOTAL_TIME);
 my $http_SIZE_DOWN = $curl->getinfo(CURLINFO_SIZE_DOWNLOAD);
 my $http_SPEED_DOWN = $curl->getinfo(CURLINFO_SPEED_DOWNLOAD);

 printf "local_time: %s, http_code: %d, dns_time: %.3fms, conn_time: %.3fms, pre_tran_time: %.3fms, start_tran_time: %.3fms, total_time: %.3fms, size_download: %dB, speed_download: %dB/s",($st,$http_code,$http_dns_time,$http_conn_time,$http_PRE_TRAN_time,$http_START_TRAN_time,$http_TOTAL_time,$http_SIZE_DOWN,$http_SPEED_DOWN);
 write;

 format STDOUT_TOP=
 站点各类响应时间明细-@||
 $%
 =========================
 +---------------------+------+-------------+--------------+--------------------------+------------------------+-------------+-----------+------------+
 | 本地时间 | 状态 | DNS解析时间 | 建立连接时间 | 从建立连接到准备传输时间 |从建立连接到开始传输时间| 整个过程时间| 下载数据量|平均下载速度|
 +---------------------+------+-------------+--------------+--------------------------+------------------------+-------------+-----------+------------+
 .

 format STDOUT=
 |@<<<<<<<<<<<<<<<<<<<<| @<<<<| @<<<<<<<<<<<| @<<<<<<<<<<<<| @<<<<<<<<<<<<<<<<<<<<<<<<| @<<<<<<<<<<<<<<<<<<<<<<| @<<<<<<<<<<<| @<<<<<<<<<| @<<<<<<<<<<|
 $st,$http_code,$http_dns_time."ms",$http_conn_time."ms",$http_PRE_TRAN_time."ms",$http_START_TRAN_time."ms",$http_TOTAL_time."ms",$http_SIZE_DOWN."B",$http_SPEED_DOWN."B/s"
 +---------------------+------+-------------+--------------+--------------------------+------------------------+--------------+----------+------------+
 .
}else{
 print "Error: $err\n";
}

sub getTime()
{
 my @time=(localtime)[5,4,3,2,1,0];
 $time[0]+=1900;
 $time[1]+=1;
 return sprintf("%04u-%02u-%02u %02u:%02u:%02u",@time);
}

shell命令下也有相同的命令如下所示：
 

复制代码 代码如下:

# curl -o /dev/null -s -w %{http_code}:%{http_connect}:%{time_namelookup}:%{time_connect}:%{time_pretransfer}:%{time_starttransfer}:%{time_total}:%{size_download}:%{speed_download} www.ttlsa.com

不解释了，具体参见 man curl

使用 cURL 获取站点的各类响应时间 – dns解析时间,响应时间,传输时间

复制代码 代码如下:

curl -o /dev/null -s -w %{http_code}:%{http_connect}:%{content_type}:%{time_namelookup}:%{time_redirect}:%{time_pretransfer}:%{time_connect}:%{time_starttransfer}:%{time_total}:%{speed_download} digdeeply.org

这是一个本人博客站点执行 curl 命令的情况。输出通常是 HTML 代码，通过 -o 参数发送到 /dev/null。-s 参数去掉所有状态信息。-w 参数让 curl 输出的计时器的状态信息。



一次http请求中的各个时间段-dns解析,等待服务器响应,获取内容等

下边对-w参数做个详细的解释，由我(DigDeeply)翻译。有不对的地方请大家指出。(英文原文：http://curl.haxx.se/docs/manpage.html)
以下是可用的变量名：

　-w, --write-out
　以下变量会按CURL认为合适的格式输出，输出变量需要按照%{variable_name}的格式，如果需要输出%，double一下即可，即%%，同时，\n是换行，\r是回车，\t是TAB。

url_effective The URL that was fetched last. This is most meaningful if you've told curl to follow location: headers.

filename_effective The ultimate filename that curl writes out to. This is only meaningful if curl is told to write to a file with the --remote-name or --output option. It's most useful in combination with the --remote-header-name option. (Added in 7.25.1)

http_code http状态码，如200成功,301转向,404未找到,500服务器错误等。(The numerical response code that was found in the last retrieved HTTP(S) or FTP(s) transfer. In 7.18.2 the alias response_code was added to show the same info.)

http_connect The numerical code that was found in the last response (from a proxy) to a curl CONNECT request. (Added in 7.12.4)

time_total 总时间，按秒计。精确到小数点后三位。 （The total time, in seconds, that the full operation lasted. The time will be displayed with millisecond resolution.）

time_namelookup DNS解析时间,从请求开始到DNS解析完毕所用时间。(The time, in seconds, it took from the start until the name resolving was completed.)

time_connect 连接时间,从开始到建立TCP连接完成所用时间,包括前边DNS解析时间，如果需要单纯的得到连接时间，用这个time_connect时间减去前边 time_namelookup时间。以下同理，不再赘述。(The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.)

time_appconnect 连接建立完成时间，如SSL/SSH等建立连接或者完成三次握手时间。(The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed. (Added in 7.19.0))

time_pretransfer 从开始到准备传输的时间。(The time, in seconds, it took from the start until the file transfer was just about to begin. This includes all pre-transfer commands and negotiations that are specific to the particular protocol(s) involved.)

time_redirect 重定向时间，包括到最后一次传输前的几次重定向的DNS解析，连接，预传输，传输时间。(The time, in seconds, it took for all redirection steps include name lookup, connect, pretransfer and transfer before the final transaction was started. time_redirect shows the complete execution time for multiple redirections. (Added in 7.12.3))

time_starttransfer 开始传输时间。在发出请求之后，Web 服务器返回数据的第一个字节所用的时间(The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pretransfer and also the time the server needed to calculate the result.)

size_download 下载大小。(The total amount of bytes that were downloaded.)

size_upload 上传大小。(The total amount of bytes that were uploaded.)

size_header 下载的header的大小(The total amount of bytes of the downloaded headers.)

size_request 请求的大小。(The total amount of bytes that were sent in the HTTP request.)

speed_download 下载速度，单位-字节每秒。(The average download speed that curl measured for the complete download. Bytes per second.)

speed_upload 上传速度,单位-字节每秒。(The average upload speed that curl measured for the complete upload. Bytes per second.)

content_type 就是content-Type，不用多说了，这是一个访问我博客首页返回的结果示例(text/html; charset=UTF-8)；(The Content-Type of the requested document, if there was any.)

num_connects Number of new connects made in the recent transfer. (Added in 7.12.3)

num_redirects Number of redirects that were followed in the request. (Added in 7.12.3)

redirect_url When a HTTP request was made without -L to follow redirects, this variable will show the actual URL a redirect would take you to. (Added in 7.18.2)

ftp_entry_path The initial path libcurl ended up in when logging on to the remote FTP server. (Added in 7.15.4)

ssl_verify_result ssl认证结果，返回0表示认证成功。( The result of the SSL peer certificate verification that was requested. 0 means the verification was successful. (Added in 7.19.0))

若多次使用-w参数，按最后一个的格式输出。If this option is used several times, the last one will be used.