Node.js Process beforeExit事件

‘beforeExit’是在process模块中的Process类的事件，当Node.js清空其事件循环并没有额外的工作要安排时，会触发该事件。

语法:

Event: 'beforeExit'

参数： 此事件不接受任何参数。

返回值： 此事件没有返回值，只返回一个回调函数以供进一步操作。

示例1：

index.js

// Node.js program to demonstrate the   
// Process 'beforeExit' Event 
  
// Importing process module 
const process = require('process'); 
  
// Event 'beforeExit' 
process.on('beforeExit', (code) => { 
   console.log('Process beforeExit event with code: ', code); 
}); 
  
// Event 'exit' 
process.on('exit', (code) => { 
   console.log('Process exit event with code: ', code); 
}); 
  
// Display the first message  
console.log('This message is displayed first.');

使用以下命令运行 index.js 文件：

node index.js

输出:

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

示例2:

index.js

// Node.js program to demonstrate the   
// Process 'beforeExit' Event 
  
// Importing process module 
const process = require('process'); 
  
// Updating the exit code 
process.exitCode = 100; 
  
// Event 'beforeExit' 
process.on('beforeExit', (code) => { 
   console.log('Process beforeExit event with code: ', code); 
}); 
  
// Display the first message  
console.log('This message is displayed first.');

使用以下命令运行 index.js 文件：

node index.js

输出：

This message is displayed first.
Process beforeExit event with code:  100

参考： https://nodejs.org/dist/latest-v16.x/docs/api/process.html#process_event_beforeexit