Synchronous logging with Node.js

Question

I am simply to create some synchronous logging with Node.js.

I believe console.log is synchronous, but I am looking to use process.stdout, a writable stream.

This is what I have so far:

var messages = [];
var okToWrite = true;

process.stdout.on('finish', function () {

    okToWrite = true;
    if (messages.length > 0) {
        runnerLog(messages.pop());
    }

});

module.exports = function runnerLog(data) {

    if (okToWrite) {
        okToWrite = false;
        process.stdout.write(data);
        process.stdout.end();
    }
    else {
        messages.push(data);
    }

};

the problem is that the finish event is never fired, and I also tried listening for the drain event, but that didn't seem to be fired either. Calling process.stdout.end() just seemed to cause problems. Should I be calling process.stdout.flush()?

I am not sure if I need synchronous logging, but either way this code will not lock up the event loop as I am using async I/O and not waiting for anything, etc. It's all evented.

From the docs for Node.js process, it looks like calling end() will throw and finish never gets called:

https://nodejs.org/api/process.html#process_process_stdout

so perhaps I should use a different writable stream other than process.stdout and pipe it to process.stdout? No idea.

Answer 1

It appears that process.stdout.write, at least when directed at a terminal/console is already synchronous. There doesn't appear to be a need to add anything. Furthermore it doesn't appear that the process.stdout stream fires the events needed to make my original design for sync logging possible, as outlined in my question.