Samir Manjiyani

Mohammed Salman Khan

Add your custom CSS or javascript/jquery using “Custom WP CSS & JS” plugin to any theme without creating any extra CSS or JS files.
Benefits of Plugin 
* Easy to use. 
* Option to select placement (header or footer) to insert your custom JS. 
* Built with Syntax Code Highlighter. 
* Option to add custom CSS for WP Dashboard.
For Syntax Code Highlighter credits goes to <a href="https://codemirror.net/5/" rel="nofollow ugc">codemirror.net</a>

Custom WP CSS & JS

otimo

A lightweight plugin to add custom CSS, JS/Javascript to any theme. This plugin also gives you an ability to insert JS in header or footer.

Scott Reilly

Ever want to introduce custom dynamic functionality to your WordPress admin pages and otherwise harness the power of JavaScript? Any modification you may want to do with JavaScript can be facilitated via this plugin.
Using this plugin you’ll easily be able to define additional JavaScript (inline and/or by URL) to be added to all administration pages. You can define JavaScript to appear inline in the admin head, admin footer (recommended), or in the admin footer within a jQuery <code>jQuery(document).ready(function($)) {}</code> section, or reference JavaScript files to be linked in the page header. The referenced JavaScript files will appear in the admin head first, listed in the order defined in the plugin’s settings. Then any inline admin head JavaScript is added to the admin head. All values can be filtered for advanced customization (see Filters section).
Links: <a href="https://coffee2code.com/wp-plugins/add-admin-javascript/" rel="nofollow ugc">Plugin Homepage</a> | <a href="https://wordpress.org/plugins/add-admin-javascript/" rel="ugc">Plugin Directory Page</a> | <a href="https://github.com/coffee2code/add-admin-javascript/" rel="nofollow ugc">GitHub</a> | <a href="https://coffee2code.com" rel="nofollow ugc">Author Homepage</a>
<h3>Hooks</h3>
The plugin exposes four filters for hooking. Typically, code making use of filters should ideally be put into a mu-plugin or site-specific plugin (which is beyond the scope of this readme to explain). Bear in mind that most of the features controlled by these filters are configurable via the plugin’s settings page. These filters are likely only of interest to advanced users able to code.
c2c_add_admin_js_files (filter)
The ‘c2c_add_admin_js_files’ filter allows programmatic modification of the list of JavaScript files to enqueue in the admin.
Arguments:
<ul>
<li>$files (array): Array of JavaScript files.</li>
</ul>
Example:
<pre><code>/**
 * Adds a JavaScript file to be enqueued in the WP admin.
 *
 * @param array $files Array of files.
 * @return array
 */
function my_admin_js_files( $files ) {
 $files[] = 'http://ajax.googleapis.com/ajax/libs/yui/2.8.1/build/yuiloader/yuiloader-min.js';
 return $files;
}
add_filter( 'c2c_add_admin_js_files', 'my_admin_js_files' );
</code></pre>
c2c_add_admin_js_head (filter)
The ‘c2c_add_admin_js_head’ filter allows customization of the JavaScript that should be added directly to the admin page head.
Arguments:
<ul>
<li>$js (string): JavaScript code (without <code><script></code> tags).</li>
</ul>
Example:
<pre><code>/**
 * Adds JavaScript code to be added to the admin page head.
 *
 * @param string $js JavaScript code.
 * @return string
 */
function my_add_head_js( $js ) {
 $js .= "alert('Hello');";
 return $js;
}
add_filter( 'c2c_add_admin_js_head', 'my_add_head_js' );
</code></pre>
c2c_add_admin_js_footer (filter)
The ‘c2c_add_admin_js_footer’ filter allows customization of the JavaScript that should be added directly to the admin footer.
Arguments:
<ul>
<li>$js (string): JavaScript code (without <code><script></code> tags).</li>
</ul>
Example:
<pre><code>/**
 * Adds JavaScript code to be added to the admin footer.
 *
 * @param string $js JavaScript code.
 * @return string
 */
function my_add_footer_js( $js ) {
 $js .= "alert('Hello');";
 return $js;
}
add_filter( 'c2c_add_admin_js_footer', 'my_add_footer_js' );
</code></pre>
c2c_add_admin_js_jq (filter)
The ‘c2c_add_admin_js_jq’ filter allows customization of the JavaScript that should be added directly to the admin footer within a jQuery document ready function.
Arguments:
<ul>
<li>$jq_js (string): JavaScript code (without <code><script></code> tags or jQuery document ready function).</li>
</ul>
Example:
<pre><code>/**
 * Adds jQuery code to be added to the admin footer.
 *
 * @param string $jq_js jQuery code.
 * @return string
 */
function my_add_jq( $js_jq ) {
 $js_jq .= "$('.hide_me').hide();";
 return $js_jq;
}
add_filter( 'c2c_add_admin_js_jq', 'my_add_jq' );
</code></pre>

Add Admin JavaScript

Interface for easily defining additional JavaScript (inline and/or by URL) to be added to all administration pages.

Custom WP CSS & JS vs Add Admin JavaScript