@mashthekeys/console-buffer

Buffer calls to console.log, console.warn, etc. for deferred logging in NodeJS and web browsers. Forked to provide ConsoleBuffer constructor independently of replacing the global console.

Description

Calls to console methods are synchronous, and as such, will block the event loop while the data is being written to a file, terminal, socket, pipe, etc.

This module provides a seamless, drop-in buffer for all calls to the following console functions, and automatically flushes the buffer when it exceeds a certain size (8k by default). In NodeJS, the buffer also flushes when the process exits.

console.log
console.info
console.warn
console.error
console.table

Building for Browsers

Bundle index.js with Browserify in standalone mode, which should include a copy of the NodeJS util module to be used inside this module. The main bundle (console-buffer.js) and an UglifyJS2 minified version (console-buffer.min.js) will be saved to the dist directory.

You can just run the included NPM script which does this:

npm run bundle

Example

In NodeJS

require('@mashthekeys/console-buffer')(console);
console.log('Hello'); // Buffered
console.log('world'); // Buffered
// Flushed at exit or 8k of data

Customization

Patch custom console

To patch a custom console or logger instance, pass the instance as the first parameter.

const logger = require('some-package')();

const buffer = require('@mashthekeys/console-buffer')(logger);
logger.log('Hello'); // Buffered
logger.log('world'); // Buffered
// Flushed at exit or 8k of data
// or by calling buffer.flush();

Buffer Size Limit

You can specify an alternative buffer size to use for automatic flushing like this:

require('@mashthekeys/console-buffer')(console, 4096); // Buffer will flush at 4k

Prefixing Logs

You can specify a string or callback function which returns a string which will prefix all logs.

Specify a string. Here, all log statements will be prepended MyLog: when flushed:

require('@mashthekeys/console-buffer')(console, 4096, 'MyLog: ');

Specify a callback function which returns a string. Here, all log statements will be prepended by 2021-06-27T12:44:46.123Z: as an example:

require('@mashthekeys/console-buffer')(console, 4096, function() {
	return new Date().toISOString() + ': ';
});

Manually Flushing the Buffer

This module also exposes the flush function used to flush all buffers, so you can manually invoke a flush:

const logBuffer = require('@mashthekeys/console-buffer')(console);
console.log('hello'); // Buffered
console.log('world'); // Buffered
logBuffer.flush(); // Flushed

Also, you can specify an interval to automatically flush all buffers so logs don't get held in memory indefinitely.

const logBuffer = require('@mashthekeys/console-buffer')(console);
setInterval(function() {
  logBuffer.flush();
}, 5000); // Flush every 5 seconds

This will flush automatically at 8k of data as well as every 5 seconds.

Flushing the Buffer Without Logging

logBuffer.clear() will empty the contents of the buffer without logging them to the console.