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Getting started with JavaScript logging

Demos and sample code

The Basics

After you have installed JSNLog, add this to your JavaScript code to send a log message to your server side log: 

JL().fatal("log message");

JL() returns a nameless logger, called the root logger. In your server side log, it will be called ClientRoot.

You can log objects as well: 

JL().fatal({"i": 5, "j": 6});

Named loggers

To make it easier to track where in your code the message was logged, give your loggers names. For example: 

JL("function1.logger1").warn("log message");

Message severity

JSNLog is very similar to Log4J / Log4Net. It uses the same severities: TRACE, DEBUG, INFO, WARN, ERROR or FATAL.

For example: 

JL().trace("a trace message");

Set logger options

JSNLog has many features that help you reduce log traffic by only logging useful information. For example: 

var logger = JL();
logger.setOptions({
    "userAgentRegex": "MSIE 7|MSIE 8"
});

logger.trace("Only IE7 and IE8 will send this message.");

Log exceptions in a try-catch block

JSNLog logs uncaught exceptions for you out of the box. You can add to this by catching exceptions in a try-catch block and then logging the exception (details): 

try {
    ... dodgy code
} catch (e) {
    JL().fatalException("something went wrong!", e);
}

Next Step

Documentation Menu

  1. Installation
  2. Getting Started
  3. Configuration
    1. On the client
    2. On the server
      1. JSNLog
      2. Logger
      3. AjaxAppender
      4. ConsoleAppender
  4. How To
    1. Adding request headers
    2. AJAX error handling
    3. Angular 2+ logging to the server
    4. AngularJs Error Handling
    5. Console log
    6. Content Security Policy (CSP)
    7. Setting the url to send logs to
    8. Logging cyclic references
    9. Demos and sample code
    10. Lost connection handling
    11. JavaScript Error Handling
    12. Javascript Try Catch
    13. Loading jsnlog.js
      1. AMD
      2. Browserify
      3. Bundles
      4. Free CDN
      5. CommonJS
      6. ES6
      7. Script tag
      8. SystemJS
    14. Log Message Batching
    15. Log Message Format
    16. Numeric Severities
    17. Obfuscated Script Errors
    18. Using Request Ids
    19. Structured JavaScript Logging
  5. jsnlogjs.js
    1. AjaxAppender Object
      1. sendBatch Method
      2. setOptions Method
    2. __jsnlog_configure function
    3. ConsoleAppender Object
      1. sendBatch Method
      2. setOptions Method
    4. Exception Object
    5. JL Namespace and Method
      1. createAjaxAppender Method
      2. createConsoleAppender Method
      3. getAllLevel Method
      4. getDebugLevel Method
      5. getErrorLevel Method
      6. getFatalLevel Method
      7. getInfoLevel Method
      8. getOffLevel Method
      9. getTraceLevel Method
      10. getWarnLevel Method
      11. JL Method
      12. setOptions Method
    6. Logger Object
      1. debug Method
      2. error Method
      3. fatal Method
      4. fatalException Method
      5. info Method
      6. log Method
      7. setOptions Method
      8. trace Method
      9. warn Method
  6. JavascriptLogging Class
    1. Configure Method
    2. OnLogging Event
    3. RequestId Method
    4. SetJsnlogConfiguration Method
  7. Tag Helpers
    1. jl-javascript-logger-definitions