JFG Media

The plugin catches most JS errors, logs them, and displays them in a dashboard widget.
Here are some of its features:
<ul>
<li>
Except for the plugin settings, there is no database storage involved. Log is written in a “.log” file.
</li>
<li>
Display latest JS errors in a dashboard widget.
</li>
<li>
Refresh errors from the dashboard widget.
</li>
<li>
See the full error log on a separate page.
</li>
<li>
Ignore errors if the user agent contains a specific string.
</li>
<li>
Ignore errors if the error contains a specific string.
</li>
<li>
Ignore errors if the script url contains a specific string.
</li>
<li>
See which page and which script triggered the errors.
</li>
<li>
Choose the maximum amount of errors to log per page load.
</li>
<li>
Exclude logging errors from specific post types.
</li>
<li>
Choose how ajax calls are made.
</li>
</ul>
<h4>Developer hooks and filters</h4>
The plugin cleans the log every 24 hours, to only keep the last 100 entries. 
You may use the “jserrlog_max_log_entries” WP filter to enable more or less entries, by returning an integer: <code>add_filter('jserrlog_max_log_entries',function(){return 200;})</code>
Alter error data: 
You may use the “jserrlog_pre_insert_error” WP filter to modify the error data before it’s inserted into the log file: <code>add_filter('jserrlog_pre_insert_error',function($error_data){return $error_data;})</code>
Trigger integrations: 
You may use the “jserrlog_after_log” WP hook to trigger an action (Slack notification, etc.) after an error was logged: <code>add_action('jserrlog_after_log',function($error_data){//do something})</code>
Backup old errors: 
You may use the “jserrlog_before_log_maintenance” WP hook to trigger an action (archive errors, etc.) before old errors are deleted: <code>add_action('jserrlog_before_log_maintenance',function($errors){//do something})</code>
<h4>Multisite</h4>
The plugin works with multisite. There’s one error log per site.

JS Error Logger

Logs front-end javascript errors, and displays them in a dashboard widget

Janis Elsts

This plugin adds a Dashboard widget that displays the latest messages from your PHP error log. It can also send you email notifications about newly logged errors.
Features
<ul>
<li>Automatically detects error log location.</li>
<li>Explains how to configure PHP error logging if it’s not enabled yet.</li>
<li>The number of displayed log entries is configurable.</li>
<li>Sends you email notifications about logged errors (optional).</li>
<li>Configurable email address and frequency.</li>
<li>You can easily clear the log file.</li>
<li>The dashboard widget is only visible to administrators.</li>
<li>Optimized to work well even with very large log files.</li>
</ul>
Usage
Once you’ve installed the plugin, go to the Dashboard and enable the “PHP Error Log” widget through the “Screen Options” panel. The widget should automatically display the last 20 lines from your PHP error log. If you see an error message like “Error logging is disabled” instead, follow the displayed instructions to configure error logging.
Email notifications are disabled by default. To enable them, click the “Configure” link in the top-right corner of the widget and enter your email address in the “Periodically email logged errors to:” box. If desired, you can also change email frequency by selecting the minimum time interval between emails from the “How often to send email” drop-down.

Error Log Monitor

Thank you, a very good and useful plugin for catching and fixing bugs. I bought a paid version, which still has convenient functionality. I also prepared a translation into Russian, which will help other users to use this plugin. Good luck)

Great and useful plugin


It is certainly useful and has a few options but installation is manual.  It doesn't have any display log option to view filtered out messages.  Email notification doesn't seem to work.



I'm not sure about those people complaining about no clean uninstall, I don't see how they could expect that given that there was no installation done by the plugin (therefore no "clean install" either)...


Quite Good but No Display full Log Option (or other filtering)


In spite of repeated support threads about it, this plugin doesn't limit to the log file size.  Twice it's used all available storage and caused a site to crash.   Today, a 100GB log file.This shouldn't be a fancy feature, it's basic best practice to code plugins in ways that don't crash sites.The widget itself is otherwise handy and convenient.  


Crashed site


Nice plugin! Makes it easy to keep up with errors.


Useful plugin

Adds a Dashboard widget that displays the latest messages from your PHP error log. It can also send logged errors to email.

JS Error Logger vs Error Log Monitor