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Add Admin JavaScript

By Scott Reilly

Description

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 jQuery(document).ready(function($)) {} 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: Plugin Homepage | Plugin Directory Page | GitHub | Author Homepage

Hooks

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:

  • $files (array): Array of JavaScript files.

example:

/**
 * 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' );

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:

  • $js (string): JavaScript code (without <script> tags).

example:

/**
 * 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' );

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:

  • $js (string): JavaScript code (without <script> tags).

example:

/**
 * 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' );

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:

  • $jq_js (string): JavaScript code (without <script> tags or jQuery document ready function).

example:

/**
 * 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' );

Screenshots

  • A screenshot of the plugin's admin settings page.

Installation

  1. Install via the built-in WordPress plugin installer. Or download and unzip add-admin-javascript.zip inside the plugins directory for your site (typically wp-content/plugins/)
  2. Activate the plugin through the ‘Plugins’ admin menu in WordPress
  3. Go to “Settings” -> “Admin JavaScript” and add some JavaScript to be added into all admin pages. (You can also use the “Settings” link in the plugin’s entry on the admin “Plugins” page).

FAQ

How can I edit the plugin’s settings in the event I supplied JavaScript that prevents the admin pages from properly loading or being seen?

It is certainly possible that you can put yourself in an unfortunate position by supplying JavaScript that could render the admin (in whole or in part) inoperable or hidden, making it seeminly impossible to fix or revert your changes. Fortunately, there are a number of approaches you can take to correct the problem.

The recommended approach is to visit the URL for the plugin’s settings page, but appended with a special query parameter to disable the output of its JavaScript. The plugin’s settings page would typically be at a URL like https://example.com/wp-admin/options-general.php?page=add-admin-javascript%2Fadd-admin-javascript.php. Append &c2c-no-js=1 to that, so that the URL is https://example.com/wp-admin/options-general.php?page=add-admin-javascript%2Fadd-admin-javascript.php&c2c-no-js=1 (obviously change example.com with the domain name for your site).

There are other approaches you can use, though they require direct database or server filesystem access:

  • Disable JavaScript in your browser and revist the page. With JavaScript disabled, any JavaScript defined by the plugin would have no effect for you. Fix the JavaScript you defined and then re-enabled JavaScript for your browser.
  • In the site’s wp-config.php file, define a constant to disable output of the plugin-defined JavaScript: define( 'C2C_ADD_ADMIN_JAVASCRIPT_DISABLED', true );. You can then visit the site’s admin. Just remember to remove that line after you’ve fixed the JavaScript (or at least change “true” to “false”). This is an alternative to the query parameter approach described above, though it persists while the constant remains defined. There will be an admin notice on the plugin’s setting page to alert you to the fact that the constant is defined and effectively disabling the plugin from adding any JavaScript.
  • Presuming you know how to directly access the database: within the site’s database, find the row with the option_name field value of c2c_add_admin_javascript and delete that row. The settings you saved for the plugin will be deleted and it will be like you’ve installed the plugin for the first time.
  • If your server has WP-CLI installed, you can delete the plugin’s setting from the commandline: wp option delete c2c_add_admin_javascript

The initial reaction by some might be to remove the plugin from the server’s filesystem. This will certainly disable the plugin and prevent the JavaScript you configured through it from taking effect, restoring the access and functionality to the backend. However, reinstalling the plugin will put you back into the original predicament because the plugin will use the previously-configured settings, which wouldn’t have changed.

Can I add JavaScript I defined via a file, or one that is hosted elsewhere?

Yes, via the “Admin JavaScript Files” input field on the plugin’s settings page.

Can I limit what admin pages the JavaScript gets output on?

No, not presently. At least not directly. By default, the JavaScript is added to every admin page on the site.

However, you can preface your selectors with admin page specific class(es) on ‘body’ tag to ensure CSS only applies on certain admin pages. (e.g. jQuery('body.index-php h2').hide();).

Or, you can hook all the plugin’s filters and determine the current admin page content to decide whether the respective hook argument should be returned (and thus output) or not.

Can I limit what users the JavaScript applies to?

No, not presently. At least not directly. By default, the JavaScript is added for any user that can enter the admin section of the site.

You can hook all the plugin’s filters and determine the current user to decide whether the respective hook argument should be returned (and thus output) for the user or not.

How do I disable syntax highlighting?

The plugin’s syntax highlighting of JavaScript (available on WP 4.9+) honors the built-in setting for whether syntax highlighting should be enabled or not.

To disable syntax highlighting, go to your profile page. Next to “Syntax Highlighting”, click the checkbox labeled “Disable syntax highlighting when editing code”. Note that this checkbox disables syntax highlighting throughout the admin interface and not just specifically for the plugin’s settings page.

Does this plugin include unit tests?

Yes.

Reviews

Perfect Plugin

1 April 2021
The perfect plugin for adding admin JavaScript! I just hope the plugin gets an update for WordPress 5.7 soon as some features do not seem to be working as they used to. Regardless, thank you Scott for your fantastic work on yet another great plugin.

so simple, yet so powerful

6 February 2017
I was looking for a way of adding my own simple JS code into WP admin, without getting into system files, messing things up and what not. As I was looking for this online, I quickly came across this plugin, and it does exactly what I was looking for, no huss, no fuss. Well done for this plugin! Two thumbs up!

crashed WordPress 4.5

3 September 2016
It crashed WordPress 4.5 by: Fatal error: Call to undefined function get_userdata() in /public_html/wp-includes/user.php on line 458
Read all 5 reviews

Contributors and Developers

“Add Admin JavaScript” is open source software. The following people have contributed to this plugin.

Contributors

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Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.

Change Log

1.9.1 (2020-09-26)

  • Change: Update plugin framework to 051
    • Allow setting integer input value to include commas
    • Use number_format_i18n() to format integer value within input field
    • Update link to coffee2code.com to be HTTPS
    • Update readme_url() to refer to plugin’s readme.txt on plugins.svn.wordpress.org
    • Remove defunct line of code
  • Change: Note compatibility through WP 5.5+
  • Change: Restructure unit test file structure
    • New: Create new subdirectory phpunit/ to house all files related to unit testing
    • Change: Move bin/ to phpunit/bin/
    • Change: Move tests/bootstrap.php to phpunit/
    • Change: Move tests/ to phpunit/tests/
    • Change: Rename phpunit.xml to phpunit.xml.dist per best practices
  • Change: Add missing changelog entry for v1.9 release into readme.txt

1.9 (2020-06-26)

Highlights:

This minor release updates its plugin framework, adds a TODO.md file, updates a few URLs to be HTTPS, expands unit testing, updates compatibility to be WP 4.9 through 5.4+, and minor behind-the-scenes tweaks.

Details:

  • Change: Change class names used for admin notice to match current WP convention
  • Change: Update plugin framework to 050
    • Allow a hash entry to literally have ‘0’ as a value without being entirely omitted when saved
    • Output donation markup using printf() rather than using string concatenation
    • Update copyright date (2020)
    • Note compatibility through WP 5.4+
    • Drop compatibility with version of WP older than 4.9
  • New: Add TODO.md and move existing TODO list from top of main plugin file into it (and add more items to it)
  • Change: Tweak help text for ‘files’ setting for better phrasing and to remove extra sentence spaces
  • Change: Note compatibility through WP 5.4+
  • Change: Drop compatibility for version of WP older than 4.9
  • Change: Update links to coffee2code.com to be HTTPS
  • Unit tests:
    • New: Add tests for options_page_description()
    • New: Add test for default hooks
    • New: Add tests for setting and query param names
    • New: Label groupings of tests
    • Change: Remove unnecessary unregistering of hooks in tearDown()
    • Change: Move test_turn_on_admin() until just before first needed now that other tests can run before it
    • Change: Store plugin instance in class variable to simplify referencing it
    • Change: Use HTTPS for link to WP SVN repository in bin script for configuring unit tests (and delete commented-out code)

1.8.1 (2019-12-07)

  • Fix: Fix typo causing PHP warning. Props jhogervorst.

Full changelog is available in CHANGELOG.md.

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