Daniel Dvorkin

I’m working on a nice admin screen to config auto-logging of some common things (like wp_query in pre_get_posts and wp), and some other goodies.
To log things manually, you can use:
<pre><code>browser()->log ( $var, $label );
browser()->warn ( $var, $label );
browser()->info ( $var, $label );
browser()->error( $var, $label );
</code></pre>
Also, commandas are chainable:
<pre><code>browser()->log( 'This is a log...' )->error( '...and this is an error' );
</code></pre>
For example, to log all your main query’s query_vars:
<pre><code>add_filter( 'pre_get_posts', 'log_wp_query', 10000 );

function log_wp_query( $query ) {
 if ( $query->is_main_query() )
 browser()->log( $query->query_vars, 'pre_get_posts' );

 return $query;
}
</code></pre>
<h4>Filters</h4>
wplinb-match-wp-debug: Set to true to only log when wp_debug is true. To prevent logging when wp_debug is false:
<pre><code>add_filter( 'wplinb-match-wp-debug', '__return_true' );
</code></pre>
wplinb-enabled: To disable logging completely. It takes precedence over wplinb-match-wp-debug. To disable logging:
<pre><code>add_filter( 'wplinb-enabled', '__return_false' );
</code></pre>
<h4>Profiling</h4>
The plugin includes a really simple function to allow you to track execution time of different parts of your code.
<pre><code>browser()->timer( $key, $log = false );
</code></pre>
The first time you call this function with a given $key (string) it will start a timer, and return false. You can start as many timers as you want, using different $key values. You can ignore the second parameter for this first call.
The second time you call this function with a given $key, it will return the ellapsed time in seconds since you started this $key timer. If you set the second parameter to true, it will also log this value to the browser.
Example 1: Sequential use, log manually.
<pre><code>browser()->timer( 'Mega loop' );
for ( $i = 0; $i < 1000000; $i++ ) {
 //do something
}
$time = browser()->timer( 'Mega loop' );
browser()->log( $time, 'The mega loop took:' );
</code></pre>
Example 2: Start and end in different places, log automatically.
<pre><code>add_action( 'posts_selection', 'start_timer', 100 );
add_filter( 'the_posts', 'end_timer', 1, 2 );

function start_timer( $query ) {
 browser()->timer( 'Main query time' );
}

function end_timer( $posts, $query ) {
 browser()->timer( 'Main query time', true );
 return $posts;
}
</code></pre>
This is not a good way of measuring how much time a query takes to run, it’s just to illustrate how to use the timer.
In exactly the same way, you can use the function
<pre><code>Browser()->memory( $key, $log = false );
</code></pre>
to measure delta of memory consumption from your first call and your second call with the same $key.
Example:
<pre><code>Browser()->memory( 'testing' );
$test = array();
for ( $i = 0; $i < 100; $i++ ) {
 $test[$i] = md5( rand( 1, $i ) );
}
Browser()->memory( 'testing', true );


Browser()->memory( 'testing' );
$test = array();
for ( $i = 0; $i < 10000; $i++ ) {
 $test[$i] = md5( rand( 1, $i ) );
}
Browser()->memory( 'testing', true );
</code></pre>

WP Log in Browser

Allows you to log data from your PHP WordPress code to your browser's console.

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SwiftNinjaPro

This plugin blocks non-admin users from using inspect element, while still allowing access those with manage_options permission. 
The plugin also blocks some of the common keys(f12, ect.) and optionally can block right-clicks for non-admin users. 
Admins are unaffected by the plugin entirely. This plugin is also able to block users who open developer tools on another site, before visiting your site.
Version 3.0 update
This plugin is now fast and accurate, and should work on most browsers. 
This plugin can detect the browser console based on lag increased by opening the console. This detection is tough for a browser to prevent or get around. 
The detection runs fast, and has some resistance to lag spikes.
Lag detection does mean your site needs to have ok performance, but when testing it, I could play 10 of 10 youtube videos all at once without a false positive. 
During my tests, detection was still within the second I open dev tools, and successful if I go to the page with it already open. 
I tested this in chrome, firefox, and chromium. 
I also tested this on my somewhat slow website with tons of wordpress plugins installed (and the 10 videos at once test) without false positives.

Developer Tools Blocker

This plugin blocks non-admin users from using inspect element, while still allowing access those with manage_options permission.

WP Log in Browser vs Developer Tools Blocker