Introduction to `log-update-logger`

The log-update-logger package is a powerful tool for developers to manage logging efficiently in their JavaScript applications. It provides a collection of useful APIs that simplify logging, making it more manageable and readable. In this article, we’ll explore the key features of log-update-logger with code snippets and an application example.

Key Features and APIs

Basic Logging

Example of basic logging:

 const logger = require('log-update-logger');
logger.log('This is a log message.'); logger.info('This is an info message.'); logger.warn('This is a warning message.'); logger.error('This is an error message.'); 

Setting Log Level

You can set the log level to filter messages:

 logger.setLevel('warn');
logger.log('This will not be shown.'); logger.info('This will not be shown.'); logger.warn('This is a warning message.'); logger.error('This is an error message.'); 

Custom Log Formats

Define custom log formats:

 logger.setFormat('custom', ({ level, message }) => {
  return `[${new Date().toISOString()}] ${level.toUpperCase()}: ${message}`;
});
logger.log('This is a log message with custom format.'); 

Log File Output

Write log messages to a file:

 logger.setOutput('file', 'application.log');
logger.log('This log message will be saved to application.log.'); 

Async Logging

Example of asynchronous logging:

 const asyncLogger = async () => {
  await logger.log('This is an async log message.');
};
asyncLogger(); 

Using Loggers in Functions

Integrating loggers within functions:

 function fetchData() {
  logger.log('Fetching data...');
  // Simulate data fetch
  setTimeout(() => {
    logger.info('Data fetched successfully.');
  }, 2000);
}
fetchData(); 

Application Example

Here’s a complete example integrating the discussed features:

 const logger = require('log-update-logger');
// Set log level logger.setLevel('info');
// Set custom log format logger.setFormat('custom', ({ level, message }) => {
  return `[${new Date().toLocaleTimeString()}] ${level.toUpperCase()}: ${message}`;
});
// Function to simulate an application workflow function runApp() {
  logger.log('Starting application...');
  fetchData();
  processData();
}
// Function to fetch data function fetchData() {
  logger.log('Fetching data...');
  setTimeout(() => {
    logger.info('Data fetched successfully.');
    processData();
  }, 1000);
}
// Function to process data function processData() {
  logger.log('Processing data...');
  setTimeout(() => {
    logger.info('Data processed successfully.');
    logger.warn('Processing complete. Check the data for accuracy.');
  }, 1000);
}
// Run the application runApp(); 

By using the above example, developers can efficiently handle logging within their JavaScript applications using the log-update-logger package.

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