Title: Uncaught ReferenceError: browserPrefixes is not defined
Last modified: September 16, 2021

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# Uncaught ReferenceError: browserPrefixes is not defined

 *  Resolved [BjornB](https://wordpress.org/support/users/bjornb/)
 * (@bjornb)
 * [4 years, 8 months ago](https://wordpress.org/support/topic/uncaught-referenceerror-browserprefixes-is-not-defined/)
 * When having the “optimize js” checked, I can’t see any images on a certain page.
   I get an error in devtools:
 *     ```
       Uncaught ReferenceError: browserPrefixes is not defined
           at autoptimize_a4f0450fc0550b771025bd52a8a1d9ec.js:14
           at autoptimize_a4f0450fc0550b771025bd52a8a1d9ec.js:14
           at autoptimize_a4f0450fc0550b771025bd52a8a1d9ec.js:14
       ```
   
 * When looking at the html, the page goes from this (not js optimized):
    `<img 
   width="230" height="450" alt="alt" title="title" src="https://website.com/wp-
   content/uploads/image-name.png" data-orig-src="https://website.com/wp-content/
   uploads/image-name.png" class="img-responsive wp-image-20727 lazyautosizes lazyloaded"
   srcset="https://website.com/wp-content/uploads/image-name.png 200w, https://website.
   com/wp-content/uploads/image-name.png 230w" data-srcset="https://website.com/
   wp-content/uploads/image-name.png 200w, https://website.com/wp-content/uploads/
   image-name.png 230w" data-sizes="auto" data-orig-sizes="(max-width: 700px) 100vw,
   230px" sizes="230px">`
 * To this (js optimized):
    `<img width="230" height="450" alt="alt" title="title"
   src="https://website.com/wp-content/uploads/image-name.png" data-orig-src="https://
   website.com/wp-content/uploads/image-name.png" class="lazyload img-responsive
   wp-image-20727" srcset="data:image/svg+xml,%3Csvg%20xmlns%3D%27http%3A%2F%2Fwww.
   w3.org%2F2000%2Fsvg%27%20width%3D%27230%27%20height%3D%27450%27%20viewBox%3D%
   270%200%20230%20450%27%3E%3Crect%20width%3D%27230%27%20height%3D%27450%27%20fill-
   opacity%3D%220%22%2F%3E%3C%2Fsvg%3E" data-srcset="https://website.com/wp-content/
   uploads/image-name.png 200w, https://website.com/wp-content/uploads/image-name.
   png 230w" data-sizes="auto" data-orig-sizes="(max-width: 700px) 100vw, 230px"
   >`
 * When I un-check the “optimize js” checkbox, all is well again and the images 
   are visible.
 * WP, theme, plugins – all updated.
 * Thanks for any insights.
    -  This topic was modified 4 years, 8 months ago by [BjornB](https://wordpress.org/support/users/bjornb/).
    -  This topic was modified 4 years, 8 months ago by [BjornB](https://wordpress.org/support/users/bjornb/).
    -  This topic was modified 4 years, 8 months ago by [BjornB](https://wordpress.org/support/users/bjornb/).

Viewing 3 replies - 1 through 3 (of 3 total)

 *  Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/)
 * (@optimizingmatters)
 * [4 years, 8 months ago](https://wordpress.org/support/topic/uncaught-referenceerror-browserprefixes-is-not-defined/#post-14883553)
 * Hey [@bjornb](https://wordpress.org/support/users/bjornb/) ;
    The JS error is
   causing other JS (including the lazyload one) not to be executed resulting in
   broken images. The fix is in finding the root cause, but for me to be able to
   do that I would need your site’s URL, can you provide that?
 * frank
 *  Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/)
 * (@optimizingmatters)
 * [4 years, 8 months ago](https://wordpress.org/support/topic/uncaught-referenceerror-browserprefixes-is-not-defined/#post-14896773)
 * any news bjorn?
 *  Plugin Author [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/)
 * (@optimizingmatters)
 * [4 years, 8 months ago](https://wordpress.org/support/topic/uncaught-referenceerror-browserprefixes-is-not-defined/#post-14957985)
 * No feedback so I assume this got resolved BjornB? Feel free to follow up if you
   still encounter issues!
 * have a nice day!
    frank

Viewing 3 replies - 1 through 3 (of 3 total)

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 * ![](https://ps.w.org/autoptimize/assets/icon-256X256.png?rev=2211608)
 * [Autoptimize](https://wordpress.org/plugins/autoptimize/)
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 * 3 replies
 * 2 participants
 * Last reply from: [Optimizing Matters](https://wordpress.org/support/users/optimizingmatters/)
 * Last activity: [4 years, 8 months ago](https://wordpress.org/support/topic/uncaught-referenceerror-browserprefixes-is-not-defined/#post-14957985)
 * Status: resolved