Node.js http.ServerResponse.headersSent 属性

httpServerResponse.headersSent是 HTTP 模块中的 ServerResponse 类的内置应用程序编程接口，用于检查标头是否已发送。

句法：

const response.headersSent

参数：此属性不接受任何参数作为参数。

返回值：当且仅当发送了标头时，此属性才返回 true，否则返回 false。

示例 1：文件名-index.js

Javascript

// Node.js program to demonstrate the  
// response.headersSent() method
  
// Importing http module 
var http = require('http');
  
// Setting up PORT 
const PORT = process.env.PORT || 3000;
  
// Creating http Server 
var httpServer = http.createServer(
    function (request, response) {
  
    // Checking if response header is sent or not
    // by using headersSent method
    const value = response.headersSent;
  
    // Display result by using end() method
    response.end("Headers have been sent : "
                   + value, 'utf8', () => {
        console.log("displaying the result...");
  
        httpServer.close(() => {
            console.log("server is closed")
        })
    });
});
  
// Listening to http Server 
httpServer.listen(PORT, () => {
    console.log("Server is running at port 3000...");
});

使用以下命令运行index.js文件：

node index.js

输出：

Server is running at port 3000...
displaying the result...
server is closed

现在打开浏览器并转到http://localhost:3000/ ，您将看到以下输出：

Headers have been sent : false

示例 2：文件名-index.js

Javascript

// Node.js program to demonstrate the  
// response.headersSent() method
  
// Importing http module 
var http = require('http');
  
// Request and response handler 
const httpHandlers = (request, response) => {
  
    // Checking if response header is sent or not
    // by using headersSent method
    const value = response.headersSent;
  
    // Display result by using end() method
    response.end("Headers have been sent : "
                      + value, 'utf8', () => {
        console.log("displaying the result...");
  
        httpServer.close(() => {
            console.log("server is closed")
        })
    });
};
  
// Creating http Server 
var httpServer = http.createServer(
    httpHandlers).listen(3000, () => {
    console.log("Server is running at port 3000...");
});

使用以下命令运行index.js文件：

node index.js

输出：

Server is running at port 3000...
displaying the result...
server is closed

现在打开浏览器并转到http://localhost:3000/ ，您将看到以下输出：

Headers have been sent : false

参考： https://nodejs.org/dist/latest-v12.x/docs/api/http.html#http_response_headerssent