Title: Javascript Errors message
Last modified: July 2, 2023

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# Javascript Errors message

 *  Resolved [dennie12](https://wordpress.org/support/users/dennie12/)
 * (@dennie12)
 * [2 years, 11 months ago](https://wordpress.org/support/topic/javascript-errors-message/)
 * Hi I want to show 3rd party digital Ads on my website and I installed the Ad 
   Inserter plug-in today. I have added some Javascript code to the plug-in to create
   an Ad before content (in a post -Ad size 336 x 280) but I am receiving Javascript
   Errors message- I’m not clear what is causing this error. Can you please help?
   Thanks
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fjavascript-errors-message%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 1 replies (of 1 total)

 *  Plugin Author [Spacetime](https://wordpress.org/support/users/spacetime/)
 * (@spacetime)
 * [2 years, 11 months ago](https://wordpress.org/support/topic/javascript-errors-message/#post-16863426)
 * Error message:
 *     ```wp-block-code
       placeholder.js?ver=1.3.1:47 Uncaught TypeError: Cannot read properties of null (reading 'addEventListener')
       ```
   
 * Cause by script from plugin `optin forms`:
   `https://www.afrowomanonline.com/wp-
   content/plugins/optin-forms/js/placeholder.js?ver=1.3.1`

Viewing 1 replies (of 1 total)

The topic ‘Javascript Errors message’ is closed to new replies.

 * ![](https://ps.w.org/ad-inserter/assets/icon-256x256.jpg?rev=1502039)
 * [Ad Inserter - Ad Manager & AdSense Ads](https://wordpress.org/plugins/ad-inserter/)
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 * 1 reply
 * 2 participants
 * Last reply from: [Spacetime](https://wordpress.org/support/users/spacetime/)
 * Last activity: [2 years, 11 months ago](https://wordpress.org/support/topic/javascript-errors-message/#post-16863426)
 * Status: resolved