How can node.js process trigger a callback function when it exit?

Question

How can node.js process trigger a callback function when it exit?

That is my code, I tried two ways to trigger a callback function when process exit.

My purpose is when process exit, it can write some word to a txt file.

The way I exit process is click the 'close' button on the node.exe window,the other way is key Ctrl+C.

But both of these methods are not effective.

process.on('exit', function() {
  chatCache.each(function(i,self,length){
    util.writeJSONtoTxt(chatChache_filePath,JSON.stringify(self));
});
});
//--------------------------------------------
var stdin = process.openStdin();

process.on('SIGINT', function () {
 console.log('Got SIGINT.  Press Control-D to exit.');
 chatCache.each(function(i,self,length){
    util.writeJSONtoTxt(chatChache_filePath,JSON.stringify(self));
});
});

node.js
process

Answer 1

You have to kill the process from SIGINT handler like this :

process.on('SIGINT', function() {
 console.log('Got SIGINT.  Going to exit.');
 //Your code to execute before process kill.
 process.kill(process.pid);
});

Then it will exit when you press Ctrl+C .

process.on('exit', function() {}); is only executed when your node.js code completes executing (finishes event loop) without any errors, which will never happen if you run a server.