Title: Modify HTML output (Output Buffer)
Last modified: April 27, 2021
---
# Modify HTML output (Output Buffer)
* Resolved [Matthias Günter](https://wordpress.org/support/users/mguenter/)
* (@mguenter)
* [5 years, 1 month ago](https://wordpress.org/support/topic/modify-html-output-output-buffer/)
* Hey!
* I have a user of one of our plugins ([https://wordpress.org/plugins/real-cookie-banner/](https://wordpress.org/plugins/real-cookie-banner/)),
and there happens something strange because our plugin modifies the content via`
ob_start`, but the changes are only visible to logged-in users.
* I did some more research and found out that you offer custom filters to adjust
the output buffer: [https://docs.litespeedtech.com/lscache/lscwp/api/#modify-output-buffer-before](https://docs.litespeedtech.com/lscache/lscwp/api/#modify-output-buffer-before)
* Unfortunately, this does not help. I did a simple test with the following code
in a custom plugin (no action, just plain in `my-plugin.php`):
* ```
add_action('litespeed_buffer_after', function($content) {
return str_replace(', Auto-updates disabled
BBQ Firewall: version: 20210211, author: Jeff Starr, Auto-updates disabled
Beaver Builder Pattern Backgrounds: version: 1.4.3, author: SiteSpot Dev, Auto-updates disabled
Beaver Builder Plugin (Standard Version): version: 2.4.2.2, author: The Beaver Builder Team, Auto-updates disabled
Booster for WooCommerce: version: 5.3.9, author: Pluggabl LLC, Auto-updates disabled
Booster Plus for WooCommerce: version: 5.3.8, author: Pluggabl LLC (latest version: 5.3.9), Auto-updates disabled
Classic Editor: version: 1.6, author: WordPress Contributors, Auto-updates disabled
Disable Cart Fragments: version: 2.0, author: Optimocha, Auto-updates disabled
Embed Sendy: version: 1.3.3, author: Ram Ratan Maurya, Auto-updates disabled
Enable Media Replace: version: 3.5.0, author: ShortPixel, Auto-updates disabled
Envato Market: version: 2.0.6, author: Envato, Auto-updates disabled
Fetchify: version: 1.3.0, author: Fetchify, Auto-updates disabled
Filester - File Manager Pro: version: 1.7.2, author: Ninja Team, Auto-updates disabled
FooBox Image Lightbox: version: 2.7.16, author: FooPlugins, Auto-updates disabled
FooGallery: version: 2.0.24, author: FooPlugins, Auto-updates disabled
Format Media Titles: version: 1.0.0, author: David Gwyer, Auto-updates disabled
GPLVault Update Manager: version: 3.4.1, author: GPL Vault, Auto-updates disabled
GP Premium: version: 1.12.3, author: Tom Usborne, Auto-updates disabled
Green Popups (formerly Layered Popups): version: 7.23, author: Halfdata, Inc. (latest version: 7.25), Auto-updates disabled
Limit Login Attempts Reloaded: version: 2.21.1, author: Limit Login Attempts Reloaded, Auto-updates disabled
LiteSpeed Cache: version: 3.6.4, author: LiteSpeed Technologies, Auto-updates disabled
MailOptin - Lite: version: 1.2.35.4, author: MailOptin Team, Auto-updates disabled
PayPal for WooCommerce: version: 2.5.7, author: Angell EYE, Auto-updates disabled
PixelYourSite Microsoft UET (Bing): version: 2.1.0, author: PixelYourSite, Auto-updates disabled
PixelYourSite Pinterest: version: 3.1.1, author: PixelYourSite, Auto-updates disabled
PixelYourSite PRO: version: 8.2.1, author: PixelYourSite, Auto-updates disabled
Popup Maker: version: 1.16.1, author: Popup Maker, Auto-updates disabled
Popup Maker - Advanced Theme Builder: version: 1.2.0, author: Popup Maker, Auto-updates disabled
Real Cookie Banner: version: 1.14.1-5648, author: devowl.io, Auto-updates disabled
Real Media Library: version: 4.13.4, author: devowl.io, Auto-updates disabled
Regenerate Thumbnails: version: 3.1.5, author: Alex Mills (Viper007Bond), Auto-updates disabled
Regenerate Thumbnails Advanced: version: 2.4.0, author: ShortPixel, Auto-updates disabled
Safe SVG: version: 1.9.9, author: Daryll Doyle, Auto-updates disabled
Shortcode in Menus: version: 3.5.1, author: Gagan Deep Singh, Auto-updates disabled
Simple Social Icons: version: 3.0.2, author: StudioPress, Auto-updates disabled
Smart Slider 3 Pro: version: 3.4.1.17, author: Nextend, Auto-updates disabled
Title and Nofollow For Links: version: 1.11, author: WPKube, Auto-updates disabled
WooCommerce: version: 5.2.2, author: Automattic, Auto-updates disabled
WooCommerce - Store Exporter Deluxe: version: 4.9, author: Visser Labs, Auto-updates disabled
WooCommerce Advanced Bulk Edit: version: 4.6.2.3, author: George Iron, Auto-updates disabled
WooCommerce Amazon Pay: version: 1.13.1, author: WooCommerce, Auto-updates disabled
WooCommerce Multi Currency Premium: version: 2.1.11, author: VillaTheme, Auto-updates disabled
WooCommerce Photo Reviews Premium: version: 1.1.4.9, author: VillaTheme, Auto-updates disabled
WooCommerce Stripe Gateway: version: 5.1.0, author: WooCommerce, Auto-updates disabled
WooCommerce Table Rate Shipping: version: 4.2.1, author: Bolder Elements, Auto-updates disabled
WPC AJAX Add to Cart for WooCommerce: version: 1.3.2, author: WPClever, Auto-updates disabled
WPC Product Bundles for WooCommerce (Premium): version: 5.5.3, author: WPClever, Auto-updates disabled
Yoast Duplicate Post: version: 4.1.2, author: Enrico Battocchi & Team Yoast, Auto-updates disabled
Yoast SEO: version: 16.1.1, author: Team Yoast, Auto-updates disabled
### wp-plugins-inactive (33) ###
All-in-One WP Migration: version: 7.42, author: ServMask, Auto-updates disabled
Blog2Social: Social Media Auto Post & Scheduler: version: 6.7.2, author: Blog2Social, Adenion, Auto-updates disabled
Brindle's QuickPopPRO: version: 1.0.4, author: Brindle, Auto-updates disabled
Complianz | GDPR/CCPA Cookie Consent: version: 5.0.1, author: Really Simple Plugins, Auto-updates disabled
Connects - Sendy Addon: version: 2.1.4, author: Brainstorm Force, Auto-updates disabled
Convert Plus: version: 3.5.18, author: Brainstorm Force, Auto-updates disabled
Cookie Notice & Compliance for GDPR / CCPA: version: 2.0.4, author: Hu-manity.co, Auto-updates disabled
Download Plugins and Themes from Dashboard: version: 1.7.1, author: Algoritmika Ltd, Auto-updates disabled
Duplicator: version: 1.4.0, author: Snap Creek, Auto-updates disabled
Error Log Monitor: version: 1.7, author: Janis Elsts, Auto-updates disabled
FastDup: version: 1.2.1, author: Ninja Team, Auto-updates disabled
Flying Pages by WP Speed Matters: version: 2.4.2, author: Gijo Varghese, Auto-updates disabled
GDPR Cookie Consent: version: 2.0.1, author: WebToffee, Auto-updates disabled
Integrately for WordPress: version: 0.1, author: Integrately.com, Auto-updates disabled
Integration of Sendy with WooCommerce: version: 1.1, author: ProThoughts, Auto-updates disabled
Klarna Order Management for WooCommerce: version: 1.6.7, author: klarna, krokedil, Auto-updates disabled
Klarna Payments for WooCommerce: version: 2.4.3, author: krokedil, klarna, automattic, Auto-updates disabled
NextScripts: SNAP Pro Upgrade Helper: version: 1.5.10, author: NextScripts, Auto-updates disabled
NextScripts: Social Networks Auto-Poster: version: 4.3.20, author: NextScripts, Auto-updates disabled
Ninja Forms: version: 3.5.4, author: Saturday Drive, Auto-updates disabled
Ninja Popups: version: 4.7.5, author: ArsCode, Auto-updates disabled
Post SMTP: version: 2.0.23, author: Yehuda Hassine, Auto-updates disabled
Product Catalog Feed Pro by PixelYourSite: version: 5.1.1, author: PixelYourSite, Auto-updates disabled
ShortPixel Adaptive Images: version: 2.2.1, author: ShortPixel, Auto-updates disabled
ShortPixel Image Optimizer: version: 4.21.2, author: ShortPixel, Auto-updates disabled
TrustMate.io integration for WooCommerce: version: 1.6.2, author: TrustMate.io dev team, Auto-updates disabled
WooCommerce Abandoned Cart Recovery Premium: version: 1.0.6.2, author: VillaTheme, Auto-updates disabled
WooCommerce Side Cart Premium: version: 2.4, author: XootiX, Auto-updates disabled
Wordpress Pinterest Automatic: version: 4.14.2, author: ValvePress, Auto-updates disabled
WP-Optimize - Clean, Compress, Cache: version: 3.1.8, author: David Anderson, Ruhani Rabin, Team Updraft, Auto-updates disabled
WPC Fly Cart for WooCommerce: version: 3.0.0, author: WPClever, Auto-updates disabled
WPC Smart Quick View for WooCommerce: version: 2.6.0, author: WPClever, Auto-updates disabled
WPide: version: 2.5, author: WebFactory Ltd, Auto-updates disabled
### wp-media ###
image_editor: FooGallery_Thumb_Image_Editor_Imagick
imagick_module_version: 1650
imagemagick_version: ImageMagick 6.7.2-7 2021-04-02 Q16 http://www.imagemagick.org
file_uploads: File uploads is turned off
post_max_size: 500M
upload_max_filesize: 500M
max_effective_size: 500 MB
max_file_uploads: 20
gd_version: bundled (2.1.0 compatible)
ghostscript_version: 8.70
### wp-server ###
server_architecture: Linux 2.6.32-954.3.5.lve1.4.80.el6.x86_64 x86_64
httpd_software: LiteSpeed
php_version: 7.4.15 64bit
php_sapi: litespeed
max_input_variables: 20000
time_limit: 300
memory_limit: 512M
max_input_time: 300
upload_max_filesize: 500M
php_post_max_size: 500M
curl_version: 7.74.0 OpenSSL/1.1.1j
suhosin: false
imagick_availability: true
pretty_permalinks: true
htaccess_extra_rules: true
### wp-database ###
extension: mysqli
server_version: 10.2.37-MariaDB-log-cll-lve
client_version: mysqlnd 7.4.15
### wp-constants ###
WP_HOME: undefined
WP_SITEURL: undefined
WP_CONTENT_DIR: xxx
WP_PLUGIN_DIR: xxx
WP_MEMORY_LIMIT: 256M
WP_MAX_MEMORY_LIMIT: 512M
WP_DEBUG: false
WP_DEBUG_DISPLAY: true
WP_DEBUG_LOG: false
SCRIPT_DEBUG: false
WP_CACHE: true
CONCATENATE_SCRIPTS: false
COMPRESS_SCRIPTS: undefined
COMPRESS_CSS: undefined
WP_LOCAL_DEV: undefined
DB_CHARSET: utf8
DB_COLLATE: undefined
### wp-filesystem ###
wordpress: writable
wp-content: writable
uploads: writable
plugins: writable
themes: writable
mu-plugins: writable
```
* Is there any limitation or is this a bug?
* Regards,
Matthew 😊
Viewing 4 replies - 1 through 4 (of 4 total)
* Plugin Support [Hai Zheng⚡](https://wordpress.org/support/users/hailite/)
* (@hailite)
* [5 years, 1 month ago](https://wordpress.org/support/topic/modify-html-output-output-buffer/#post-14374934)
* Hi Matthew,
* The buffer hook works for the logged-in users, that means the hook works. Each
time when calling into that `ob_start` in [https://github.com/litespeedtech/lscache_wp/blob/dev/src/core.cls.php#L138](https://github.com/litespeedtech/lscache_wp/blob/dev/src/core.cls.php#L138)
that hook will be called always.
* In your case, I guess for guest users, it doesn’t run into that line at all.
Maybe you need to check if LSCWP runs on that page or not. You can turn on debug
log and see what logs tell.
* I tried your code
* ```
add_action('litespeed_buffer_after', function($content) {
return str_replace(' In your case, I guess for guest users, it doesn’t run into that line at all.
> Maybe you need to check if LSCWP runs on that page or not.
* The user has the following plugin installed as you can see from the site-health
export above: `LiteSpeed Cache: version: 3.6.4, author: LiteSpeed Technologies`.
This is currently the only active plugin as I deactivated the others for testing
purposes.
* > You can turn on debug log and see what logs tell.
* I just enabled debugging in the LSCWP plugin and the following gets logged when
opening the homepage as logged-in user:
* ```
04/28/21 14:24:13.014 [79.219.221.194:63840 1 0YC] 💓 ------GET HTTP/1.1 (HTTPS) /
04/28/21 14:24:13.014 [79.219.221.194:63840 1 0YC] Query String:
04/28/21 14:24:13.014 [79.219.221.194:63840 1 0YC] HTTP_REFERER: https://staging.xxxxxxxx.com/wp-admin/admin.php?page=litespeed-toolbox
04/28/21 14:24:13.014 [79.219.221.194:63840 1 0YC] Cookie _lscache_vary: admin_bar:1;logged-in:1;role:99;role_exclude_cache:1
04/28/21 14:24:13.014 [79.219.221.194:63840 1 0YC] LSCACHE_VARY_COOKIE: wmc_current_currency
04/28/21 14:24:13.090 [79.219.221.194:63840 1 0YC] [Ctrl] X Cache_control -> private ( logged in user )
04/28/21 14:24:13.191 [79.219.221.194:63840 1 0YC] [Router] get_role: administrator
04/28/21 14:24:13.191 [79.219.221.194:63840 1 0YC] [Core] ⛑️ bypass_optm: hit Role Excludes setting: administrator
04/28/21 14:24:13.221 [79.219.221.194:63840 1 0YC] [Ctrl] X Cache_control init on
04/28/21 14:24:13.904 [79.219.221.194:63840 1 0YC] [Core] Footer hook called
04/28/21 14:24:13.913 [79.219.221.194:63840 1 0YC] [Core] Footer check passed
04/28/21 14:24:13.915 [79.219.221.194:63840 1 0YC] [Ctrl] X Cache_control off - Role Excludes setting administrator
04/28/21 14:24:13.915 [79.219.221.194:63840 1 0YC] [Ctrl] X Cache_control -> no Cache
04/28/21 14:24:13.915 [79.219.221.194:63840 1 0YC] 💰 X-LiteSpeed-Cache-Control: no-cache
04/28/21 14:24:13.915 [79.219.221.194:63840 1 0YC] [Core] Footer check passed
04/28/21 14:24:13.977 [79.219.221.194:63840 1 0YC] End response
--------------------------------------------------------------------------------
```
* And if I visit the same page as logged-out (guest) user, nothing is logged. Is
this the correct behavior? For me it looks like the WordPress engine itself is
not called when visiting the website as logged-out user.
* I also tried to put the exact same code you posted to the `functions.php` but
it does not work, too. What else could I test?
* Regards,
Matthew 😊
* Plugin Support [Hai Zheng⚡](https://wordpress.org/support/users/hailite/)
* (@hailite)
* [5 years, 1 month ago](https://wordpress.org/support/topic/modify-html-output-output-buffer/#post-14375346)
* I think that is bcos your guest page is cached 🙂 You need to purge before you
can see the result, or easier way is to give the url you are visiting a QS, e.
g. [https://domain.com/?xx](https://domain.com/?xx)
* Thread Starter [Matthias Günter](https://wordpress.org/support/users/mguenter/)
* (@mguenter)
* [5 years, 1 month ago](https://wordpress.org/support/topic/modify-html-output-output-buffer/#post-14383332)
* Hi again!
* Thanks for your reply, and sorry for my wrong alert… LiteSpeed isn’t the cause,
it is Anti Spam by Cleantalk.
* /Closed. 🙂
Viewing 4 replies - 1 through 4 (of 4 total)
The topic ‘Modify HTML output (Output Buffer)’ is closed to new replies.
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* 4 replies
* 2 participants
* Last reply from: [Matthias Günter](https://wordpress.org/support/users/mguenter/)
* Last activity: [5 years, 1 month ago](https://wordpress.org/support/topic/modify-html-output-output-buffer/#post-14383332)
* Status: resolved