This code checks if a server variable exists and is not undefined, then calls its close() method if it does. It is likely used in a server or network context to properly close the server when it is no longer in use.

Run example

npm run import -- "stop express server"

stop express server

if (typeof server !== 'undefined') {
    server.close();
}

/**
 * Closes the server connection if it exists.
 *
 * @param {import('http').Server} server The server object to close.
 */
function closeServer(server) {
  // Check if the server object is not undefined
  if (server && typeof server.close === 'function') {
    // Close the server connection
    server.close();
  } else {
    // Log a warning message if the server object is invalid
    console.warn('Invalid server object. Cannot close server connection.');
  }
}

// Usage example
import http from 'http';
const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('Hello World\n');
});

// Close the server after 5 seconds
setTimeout(() => {
  closeServer(server);
}, 5000);

Code Breakdown

Functionality

This code checks if a variable named server exists, and if it does, it calls the close() method on it.

Syntax

• if (typeof server!== 'undefined') - This line checks the type of the server variable using the typeof operator and ensures it is not undefined using the !== operator.
• server.close(); - If the condition is true, this line calls the close() method on the server variable.

Context

This code snippet is likely used in a server or network context, where a server object needs to be closed when it is no longer in use.