@wisual/logger v1.2.0

@wisual/logger

This is a logging module for the front-end. At the moment it only implements simple creation of contextual and hierarchical loggers that carry over data through React.js context. It also implements some basic pretty-printing.

Basic usage

A logger can be created with LoggerFactory. It'll be cached by name & thus getting the logger is very cheap.

import { LoggerFactory } from "@wisual/logger";

const logger = LoggerFactory.getLogger("MyLogger");

logger.info("Hello world");
logger.debug("segfault");
logger.warn("Coulnd't find X");
logger.error("Oh no");

Structured data

You may pass additional data as a parameter & this will be available for the sinks to output in a structured format:

logger.info("Created user", { user, sessionId, tabId });

Hierarchical logger

Loggers are hierarchical. When creating a child, you may set extra context data on to it. Every child will inherits it's parents contexes.

import { LoggerFactory } from "@wisual/logger";

const logger = LoggerFactory.getLogger("root");

const usersServiceLogger = logger.child('UsersService', { dbBackend: 'psql', flushTimeout: 1000 });
const usersCacheLogger = usersServiceLogger.child('UsersCache', { cacheBackend: 'redis' });

usersCacheLogger.info('Cache hits in last 10 seconds', { cacheHits: 10 });
// Data available in the log:
// {
//   logger: "root>UsersService>UsersCache",
//   message: "Cache hits in last 10 seconds",
//   time: "01-03-2021T...",
//   variables: { cacheHits: 10 },
//   context: {
//     dbBackend: 'psql',
//     flushTimeout: 1000,
//     cacheBackend: 'redis',
//   }
// }

React integration

There are hooks provided for react integration.

import React from "react";
import { useLogger } from "@wisual/logger";

function MyComponent({ userId, data }: { userId: string; data: any }) {
  // Creating our logger and properly setting its context
  const logger = useLogger("MyComponent", { userId });

  // Will log on render with proper context / names
  logger.info("rendering");

  // This will use effect to log & log everytime the arguments change
  logger.onInfo("Data has changed", { data });

  // This is wrapping the children with this logger's context provider
  return logger.wrap(<div />);
}

The hierarchy of loggers will be created based on the React tree. A logger may wrap a sub-tree with wrapWithLogger:

function Router({ routeName }) {
    const routerLogger = useLogger("Router", { routeName });
    // ...
    return wrapWithLogger(
        routerLogger,
        <div>...</div>
    );
}

All calls to useLogger within the wrapped sub-tree will inherit the parent context.

Logger sinks

Sinks are implementors of the LoggerSink interface.

Tree sinks are provided:

• PrettyConsoleSink - Pretty print messages on Node.js
• PrettyBrowserSink - Pretty print messages on browser consoles, which have support for CSS
• DelegatingSink - Send messages to multiple sinks

There's no filtering currently implemented.

In addition, you'll find a tauri sink which provides rust/js logging functionality in the crates/plugin-host-gui package.

Configuring the sink

Use LoggerFactory.setSink.