Node.js proces 'beforeExit'事件用法及代码示例

事件：'beforeExit'

'beforeExit' 事件在 Node.js 清空其事件循环并且没有其他工作要安排时发出。通常情况下，Node.js 进程会在没有安排工作时退出，但在'beforeExit' 事件上注册的侦听器可以进行异步调用，从而使 Node.js 进程继续。

使用作为唯一参数传递的 process.exitCode 的值调用侦听器回调函数。

'beforeExit' 事件不会针对导致显式终止的条件发出，例如调用 process.exit() 或未捕获的异常。

'beforeExit' 不应用作'exit' 事件的替代，除非打算安排额外的工作。

import process from 'node:process';

process.on('beforeExit', (code) => {
  console.log('Process beforeExit event with code: ', code);
});

process.on('exit', (code) => {
  console.log('Process exit event with code: ', code);
});

console.log('This message is displayed first.');

// Prints:
// This message is displayed first.
// Process beforeExit event with code: 0
// Process exit event with code: 0const process = require('node:process');

process.on('beforeExit', (code) => {
  console.log('Process beforeExit event with code: ', code);
});

process.on('exit', (code) => {
  console.log('Process exit event with code: ', code);
});

console.log('This message is displayed first.');

// Prints:
// This message is displayed first.
// Process beforeExit event with code: 0
// Process exit event with code: 0