Introduction to Measure-Logger

Measure-Logger is a performance metrics logging library designed for developers who require precise, real-time insights into their application’s performance. In this guide, we cover the various APIs provided by Measure-Logger, complete with code snippets and an application example.

Getting Started

To begin, install Measure-Logger using npm or yarn:

  npm install measure-logger
  // or
  yarn add measure-logger

Basic Usage

Start by importing and initializing the logger:

  import MeasureLogger from 'measure-logger';

  const logger = new MeasureLogger({
    appName: 'MyApp',
    environment: 'production',
  });

API Examples

Log a Simple Metric

To log a simple metric:

  logger.logMetric('apiResponseTime', 200);

Log a Metric with Additional Data

To log a metric with extra contextual information:

  logger.logMetric('apiResponseTime', 200, {
    endpoint: '/api/users',
    method: 'GET',
  });

Start and Stop Timers

To measure time intervals:

  logger.startTimer('dbQueryTime');

  // Imagine this is your database query
  setTimeout(() => {
    logger.stopTimer('dbQueryTime');
  }, 300);

Use Custom Timer Identifiers

For more detailed timing:

  const queryTimerId = logger.startTimer('dbQueryTime');

  // Imagine this is your database query
  setTimeout(() => {
    logger.stopTimer('dbQueryTime', queryTimerId);
  }, 300);

Log Events

To log significant events:

  logger.logEvent('userLogin', {
    userId: '12345',
    userType: 'admin',
  });

Log Errors

To capture and log errors:

  try {
    // code that might throw an error
    throw new Error('Something went wrong');
  } catch (error) {
    logger.logError('unhandledException', error);
  }

Full Application Example

Below is an example of a simple application that uses Measure-Logger:

  import MeasureLogger from 'measure-logger';

  const logger = new MeasureLogger({
    appName: 'MyApp',
    environment: 'production',
  });

  function fetchUserData(userId) {
    const timerId = logger.startTimer('fetchUserDataTime');

    fetch(`/api/users/${userId}`)
      .then(response => response.json())
      .then(data => {
        logger.stopTimer('fetchUserDataTime', timerId);
        logger.logEvent('userDataFetched', { userId, userType: data.type });
      })
      .catch(error => {
        logger.stopTimer('fetchUserDataTime', timerId);
        logger.logError('fetchUserDataFailed', error);
      });
  }

  // Simulate a user login
  function userLogin(userId) {
    logger.logEvent('userLogin', { userId });

    fetchUserData(userId);
  }

  userLogin('12345');

By leveraging Measure-Logger, developers can gain critical insights into their application’s performance, ensuring optimal user experience and quick troubleshooting of any issues that arise.