WP Rocket's JavaScript optimization features can interfere with Mida if not configured correctly.
Mida's script needs to run as early as possible in <head> to assign visitors to experiment variants before the browser paints the page. When WP Rocket delays or bundles it, visitors see a flash of the original content before any experiment fires.
The three WP Rocket settings that can affect Mida
WP Rocket feature | Why it breaks Mida |
Minify / Combine JavaScript | Bundles Mida's script into a combined file, moving it out of |
Load JavaScript Deferred | Adds |
Delay JavaScript Execution | Holds all scripts until user interaction — Mida never fires on page load |
How to exclude Mida
Go to WordPress Admin → Settings → WP Rocket → File Optimization.
For each of the features above, find its Excluded JavaScript Files field and add: optimize.js
Under Minify JavaScript / Combine JavaScript → Excluded JavaScript Files
Under Load JavaScript Deferred → Excluded JavaScript Files
Under Delay JavaScript Execution → Excluded JavaScript Files
Not sure which features are active? Add optimize.js to all three. Adding it to a disabled feature has no effect.
Also exclude the anti-flicker inline script
If you're using Mida's anti-flicker snippet, add this to the Delay JavaScript Execution → Excluded JavaScript Files field as well: abhide
After saving, click Clear Cache in WP Rocket.
Clear cache on whole site
Go to Settings → WP Rocket → Dashboard tab and press the Clear and preload cache button.
Another way is via the WordPress tool bar (or admin bar). Roll over the WP Rocket menu link, and you will see a dropdown menu. Click on the Clear and preload cache link.
Skip all of this with the Mida WordPress plugin
The Mida A/B Testing plugin handles all of the above automatically. Install it from the WordPress plugin directory and it will take care of the correct script setup, no manual WP Rocket configuration needed.
