http.request(url[, options][, callback])


  • url <string> | <URL>
  • options <Object>
    • agent <http.Agent> | <boolean> 控制 Agent 的行为。 可能的值:
      • undefined(默认): 为此主机和端口使用 http.globalAgent
      • Agent 对象: 显式使用传入的 Agent
      • false: 使用具有默认值的新 Agent
    • auth <string> 基本身份验证,即 'user:password' 计算授权标头。
    • createConnection <Function> 当不使用 agent 选项时,生成用于请求的套接字/流的函数。 这可用于避免创建自定义 Agent 类只是为了覆盖默认的 createConnection 函数。 有关详细信息,请参阅 agent.createConnection()。 任何 Duplex 流都是有效的返回值。
    • defaultPort <number> 协议的默认端口。 默认值: 如果使用 Agent 则为 agent.defaultPort,否则为 undefined
    • family <number> 解析 hosthostname 时要使用的 IP 地址族。 有效值为 46。 当未指定时,则将使用 IP v4 和 v6。
    • headers <Object> 包含请求头的对象。
    • host <string> 要向其发出请求的服务器的域名或 IP 地址。 默认值: 'localhost'
    • hostname <string> host 的别名。 为了支持 url.parse(),如果同时指定了 hosthostname,则将使用 hostname
    • insecureHTTPParser <boolean> 使用不安全的 HTTP 解析器,当为 true 时接受无效的 HTTP 标头。 应避免使用不安全的解析器。 有关详细信息,请参阅 --insecure-http-parser默认值: false
    • localAddress <string> 用于绑定网络连接的本地接口。
    • lookup <Function> 自定义查找函数。 默认值: dns.lookup().
    • method <string> 指定 HTTP 请求方法的字符串。 默认值: 'GET'
    • path <string> 请求的路径。 应包括查询字符串(如果有)。 例如 '/index.html?page=12'。 当请求路径包含非法字符时抛出异常。 目前,只有空格被拒绝,但将来可能会改变。 默认值: '/'
    • port <number> 远程服务器的端口。 默认值: 如果有设置则为 defaultPort,否则为 80
    • protocol <string> 要使用的协议。 默认值: 'http:'
    • setHost <boolean>: 指定是否自动添加 Host 标头。 默认为 true
    • socketPath <string> Unix 域套接字(如果指定了 hostport 之一,则不能使用,因为其指定了 TCP 套接字)。
    • timeout <number>: 指定套接字超时的数值(以毫秒为单位)。 这将在连接套接字之前设置超时。
  • callback <Function>
  • 返回: <http.ClientRequest>

Node.js 为每个服务器维护多个连接以发出 HTTP 请求。 此函数允许显式地发出请求。

url 可以是字符串或 URL 对象。 如果 url 是字符串,则会自动使用 new URL() 解析。 如果是 URL 对象,则会自动转换为普通的 options 对象。

如果同时指定了 urloptions,则合并对象,options 属性优先。

可选的 callback 参数将被添加为 'response' 事件的单次监听器。

http.request() 返回 http.ClientRequest 类的实例。 ClientRequest 实例是可写流。 如果需要使用 POST 请求上传文件,则写入 ClientRequest 对象。

const postData = querystring.stringify({
  'msg': 'Hello World!'
});

const options = {
  hostname: 'www.google.com',
  port: 80,
  path: '/upload',
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded',
    'Content-Length': Buffer.byteLength(postData)
  }
};

const req = http.request(options, (res) => {
  console.log(`STATUS: ${res.statusCode}`);
  console.log(`HEADERS: ${JSON.stringify(res.headers)}`);
  res.setEncoding('utf8');
  res.on('data', (chunk) => {
    console.log(`BODY: ${chunk}`);
  });
  res.on('end', () => {
    console.log('No more data in response.');
  });
});

req.on('error', (e) => {
  console.error(`problem with request: ${e.message}`);
});

// 将数据写入请求正文
req.write(postData);
req.end();

在示例中,调用了 req.end()。 使用 http.request() 必须始终调用 req.end() 来表示请求的结束 - 即使没有数据写入请求正文。

如果在请求期间遇到任何错误(无论是 DNS 解析、TCP 级别错误还是实际的 HTTP 解析错误),都会在返回的请求对象上触发 'error' 事件。 与所有 'error' 事件一样,如果没有注册监听器,则会抛出错误。

有一些特殊的标头需要注意。

  • 发送 'Connection: keep-alive' 将通知 Node.js,服务器的连接应该持续到下一个请求。

  • 发送 'Content-Length' 标头将禁用默认的分块编码。

  • 发送 'Expect' 标头将立即发送请求头。 通常,当发送 'Expect: 100-continue' 时,应该设置超时和 'continue' 事件的监听器。 有关更多信息,请参阅 RFC 2616 第 8.2.3 节。

  • 发送授权标头将覆盖使用 auth 选项来计算基本身份验证。

使用 URL 作为 options 的示例:

const options = new URL('http://abc:xyz@example.com');

const req = http.request(options, (res) => {
  // ...
});

在成功的请求中,将按以下顺序触发以下事件:

  • 'socket'
  • 'response'
    • res 对象上的 'data',任意次数(如果响应正文为空,则根本不会触发 'data',例如,在大多数重定向中)
    • res 对象上的 'end'
  • 'close'

在连接错误的情况下,将触发以下事件:

  • 'socket'
  • 'error'
  • 'close'

如果在连接成功之前调用 req.abort(),则将按以下顺序触发以下事件:

  • 'socket'
  • (在此处调用 req.abort()
  • 'abort'
  • 使用具有消息 'Error: socket hang up' 和代码 'ECONNRESET' 的错误的 'error'
  • 'close'

如果在收到响应之后调用 req.abort(),则将按以下顺序触发以下事件:

  • 'socket'
  • 'response'
    • res 对象上的 'data',任意次数
  • (在此处调用 req.abort()
  • 'abort'
  • res 对象上的 'aborted'
  • 'close'
  • res 对象上的 'end'
  • res 对象上的 'close'

设置 timeout 选项或使用 setTimeout() 函数将不会中止请求或执行除添加 'timeout' 事件外的任何操作。

  • url <string> | <URL>
  • options <Object>
    • agent <http.Agent> | <boolean> Controls Agent behavior. Possible values:
      • undefined (default): use http.globalAgent for this host and port.
      • Agent object: explicitly use the passed in Agent.
      • false: causes a new Agent with default values to be used.
    • auth <string> Basic authentication i.e. 'user:password' to compute an Authorization header.
    • createConnection <Function> A function that produces a socket/stream to use for the request when the agent option is not used. This can be used to avoid creating a custom Agent class just to override the default createConnection function. See agent.createConnection() for more details. Any Duplex stream is a valid return value.
    • defaultPort <number> Default port for the protocol. Default: agent.defaultPort if an Agent is used, else undefined.
    • family <number> IP address family to use when resolving host or hostname. Valid values are 4 or 6. When unspecified, both IP v4 and v6 will be used.
    • headers <Object> An object containing request headers.
    • host <string> A domain name or IP address of the server to issue the request to. Default: 'localhost'.
    • hostname <string> Alias for host. To support url.parse(), hostname will be used if both host and hostname are specified.
    • insecureHTTPParser <boolean> Use an insecure HTTP parser that accepts invalid HTTP headers when true. Using the insecure parser should be avoided. See --insecure-http-parser for more information. Default: false
    • localAddress <string> Local interface to bind for network connections.
    • lookup <Function> Custom lookup function. Default: dns.lookup().
    • method <string> A string specifying the HTTP request method. Default: 'GET'.
    • path <string> Request path. Should include query string if any. E.G. '/index.html?page=12'. An exception is thrown when the request path contains illegal characters. Currently, only spaces are rejected but that may change in the future. Default: '/'.
    • port <number> Port of remote server. Default: defaultPort if set, else 80.
    • protocol <string> Protocol to use. Default: 'http:'.
    • setHost <boolean>: Specifies whether or not to automatically add the Host header. Defaults to true.
    • socketPath <string> Unix Domain Socket (cannot be used if one of host or port is specified, those specify a TCP Socket).
    • timeout <number>: A number specifying the socket timeout in milliseconds. This will set the timeout before the socket is connected.
  • callback <Function>
  • Returns: <http.ClientRequest>

Node.js maintains several connections per server to make HTTP requests. This function allows one to transparently issue requests.

url can be a string or a URL object. If url is a string, it is automatically parsed with new URL(). If it is a URL object, it will be automatically converted to an ordinary options object.

If both url and options are specified, the objects are merged, with the options properties taking precedence.

The optional callback parameter will be added as a one-time listener for the 'response' event.

http.request() returns an instance of the http.ClientRequest class. The ClientRequest instance is a writable stream. If one needs to upload a file with a POST request, then write to the ClientRequest object.

const postData = querystring.stringify({
  'msg': 'Hello World!'
});

const options = {
  hostname: 'www.google.com',
  port: 80,
  path: '/upload',
  method: 'POST',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded',
    'Content-Length': Buffer.byteLength(postData)
  }
};

const req = http.request(options, (res) => {
  console.log(`STATUS: ${res.statusCode}`);
  console.log(`HEADERS: ${JSON.stringify(res.headers)}`);
  res.setEncoding('utf8');
  res.on('data', (chunk) => {
    console.log(`BODY: ${chunk}`);
  });
  res.on('end', () => {
    console.log('No more data in response.');
  });
});

req.on('error', (e) => {
  console.error(`problem with request: ${e.message}`);
});

// Write data to request body
req.write(postData);
req.end();

In the example req.end() was called. With http.request() one must always call req.end() to signify the end of the request - even if there is no data being written to the request body.

If any error is encountered during the request (be that with DNS resolution, TCP level errors, or actual HTTP parse errors) an 'error' event is emitted on the returned request object. As with all 'error' events, if no listeners are registered the error will be thrown.

There are a few special headers that should be noted.

  • Sending a 'Connection: keep-alive' will notify Node.js that the connection to the server should be persisted until the next request.

  • Sending a 'Content-Length' header will disable the default chunked encoding.

  • Sending an 'Expect' header will immediately send the request headers. Usually, when sending 'Expect: 100-continue', both a timeout and a listener for the 'continue' event should be set. See RFC 2616 Section 8.2.3 for more information.

  • Sending an Authorization header will override using the auth option to compute basic authentication.

Example using a URL as options:

const options = new URL('http://abc:xyz@example.com');

const req = http.request(options, (res) => {
  // ...
});

In a successful request, the following events will be emitted in the following order:

  • 'socket'
  • 'response'
    • 'data' any number of times, on the res object ('data' will not be emitted at all if the response body is empty, for instance, in most redirects)
    • 'end' on the res object
  • 'close'

In the case of a connection error, the following events will be emitted:

  • 'socket'
  • 'error'
  • 'close'

If req.abort() is called before the connection succeeds, the following events will be emitted in the following order:

  • 'socket'
  • (req.abort() called here)
  • 'abort'
  • 'error' with an error with message 'Error: socket hang up' and code 'ECONNRESET'
  • 'close'

If req.abort() is called after the response is received, the following events will be emitted in the following order:

  • 'socket'
  • 'response'
    • 'data' any number of times, on the res object
  • (req.abort() called here)
  • 'abort'
  • 'aborted' on the res object
  • 'close'
  • 'end' on the res object
  • 'close' on the res object

Setting the timeout option or using the setTimeout() function will not abort the request or do anything besides add a 'timeout' event.