patch-console

What is patch-console?

The patch-console npm package allows you to intercept and modify console output in Node.js applications. This can be useful for logging, debugging, or filtering out unwanted console messages.

What are patch-console's main functionalities?

Intercepting console output

This feature allows you to intercept and modify console output. In this example, any message sent to stdout is prefixed with 'Modified: '.

const patchConsole = require('patch-console');

patchConsole((stream, data) => {
  if (stream === 'stdout') {
    return `Modified: ${data}`;
  }
  return data;
});

console.log('This is a test');

Filtering console output

This feature allows you to filter out specific console messages. In this example, any message containing the word 'ignore' will not be shown in the console.

const patchConsole = require('patch-console');

patchConsole((stream, data) => {
  if (data.includes('ignore')) {
    return '';
  }
  return data;
});

console.log('This message will be shown');
console.log('This message will be ignored');

Logging to a file

This feature allows you to log console messages to a file. In this example, all console messages are written to 'log.txt'.

const fs = require('fs');
const patchConsole = require('patch-console');

const logStream = fs.createWriteStream('log.txt', { flags: 'a' });

patchConsole((stream, data) => {
  logStream.write(data);
  return data;
});

console.log('This message will be logged to a file');

Other packages similar to patch-console

console-log-level

The console-log-level package provides a simple logger with log levels. It allows you to control the verbosity of your logs by setting different log levels (e.g., trace, debug, info, warn, error). Unlike patch-console, it does not intercept or modify existing console methods but provides its own logging methods.

winston

Winston is a versatile logging library that supports multiple transports (e.g., console, file, HTTP). It offers more advanced features compared to patch-console, such as log levels, custom formats, and multiple transports. However, it does not focus on intercepting and modifying console output directly.

log4js

Log4js is another comprehensive logging library that supports various appenders (e.g., console, file, SMTP). It provides a more structured approach to logging with categories and levels. Similar to winston, it does not intercept console output but offers extensive logging capabilities.

README

patch-console

Patch console methods to intercept output

Install

$ npm install patch-console

Usage

import patchConsole from 'patch-console';

const restore = patchConsole((stream, data) => {
	// stream = 'stdout'
	// data = "Hello World"
});

console.log('Hello World');

// Restore original methods
restore();

API

patchConsole(callback)

After this function is called, output from console methods will be intercepted and won't show up in the actual stdout or stderr stream. To restore original console methods and stop intercepting output, call the function which patchConsole() returns.

callback

Type: Function

Function that will be called when output from one of the console methods is intercepted. First argument is name of the stream ("stdout" or "stderr"), second argument is output itself.

Console methods

This module intercepts the following methods:

• console.assert()
• console.count()
• console.countReset()
• console.debug()
• console.dir()
• console.dirxml()
• console.error()
• console.group()
• console.groupCollapsed()
• console.groupEnd()
• console.info()
• console.log()
• console.table()
• console.time()
• console.timeEnd()
• console.timeLog()
• console.trace()
• console.warn()