console_log

This module provides a WSGI middleware that allows you to log to the browser console from Python:

import logging

from flask import Flask

from console_log import ConsoleLog

console = logging.getLogger('console')
console.setLevel(logging.DEBUG)

app = Flask(__name__)

@app.route('/')
def hello():
    logger.error('Error logged from Python')
    logger.warning('Warning logged from Python')
    logger.info('Info logged from Python')
    logger.debug('Debug logged from Python')
    logger.debug({'foo': ['bar', 'baz']})
    return "Hello World!"

app.wsgi_app = ConsoleLog(app.wsgi_app, console)

The logged messages will then show up in the browser console:

How it works

The new WSGI app does two things:

1. Creates a websocket backchannel.
2. Injects Javascript code into HTML responses, fetching data from the websocket channel and logging them to console.