Title: Avoid serving legacy JavaScript to modern browsers
Last modified: November 11, 2020

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# Avoid serving legacy JavaScript to modern browsers

 *  Resolved [sarangsss29](https://wordpress.org/support/users/sarangsss29/)
 * (@sarangsss29)
 * [5 years, 7 months ago](https://wordpress.org/support/topic/avoid-serving-legacy-javascript-to-modern-browsers/)
 * I ma getting Pagespeed Insight warnings on all the posts where the Meow lightbox
   and Meow Gallery plugins are working
    **PSI link:** [https://developers.google.com/speed/pagespeed/insights/?url=https%3A%2F%2Fwww.androidsage.com%2F2020%2F10%2F14%2Fdownload-iphone-12-pro-max-wallpapers%2F&tab=mobile&hl=en](https://developers.google.com/speed/pagespeed/insights/?url=https%3A%2F%2Fwww.androidsage.com%2F2020%2F10%2F14%2Fdownload-iphone-12-pro-max-wallpapers%2F&tab=mobile&hl=en)
 * **Errors:**
    Avoid serving legacy JavaScript to modern browsers
 * Polyfills and transforms enable legacy browsers to use new JavaScript features.
   However, many aren’t necessary for modern browsers. For your bundled JavaScript,
   adopt a modern script deployment strategy using module/nomodule feature detection
   to reduce the amount of code shipped to modern browsers, while retaining support
   for legacy browsers. Learn More
 * **Sceenshot:**
    [http://prnt.sc/vh6dyr](http://prnt.sc/vh6dyr)
 * The links are related to Lightbox and Gallery plugin while testing the linked
   URL. Is it possible to fix this?
    -  This topic was modified 5 years, 7 months ago by [sarangsss29](https://wordpress.org/support/users/sarangsss29/).
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Favoid-serving-legacy-javascript-to-modern-browsers%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

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

 *  Plugin Author [Jordy Meow](https://wordpress.org/support/users/tigroumeow/)
 * (@tigroumeow)
 * [5 years, 6 months ago](https://wordpress.org/support/topic/avoid-serving-legacy-javascript-to-modern-browsers/#post-13657237)
 * Hi,
 * The part of the code which is mentioned here is only 0.1kb 🙂 So it’s super tiny(
   especially that this code is compressed when going through the network). For 
   the rest, I am not so sure, indeed, you have a lot more things running. But the
   Lightbox part is clearly not the problem in the analysis of your website.
 *  Thread Starter [sarangsss29](https://wordpress.org/support/users/sarangsss29/)
 * (@sarangsss29)
 * [5 years, 6 months ago](https://wordpress.org/support/topic/avoid-serving-legacy-javascript-to-modern-browsers/#post-13661449)
 * Hi [@tigroumeow](https://wordpress.org/support/users/tigroumeow/)
    Thanks for
   the reply. First of all, got a great plugin there. Thanks for that. My concern
   is more about the warning itself “legacy JavaScript to modern browsers” Doesn’t
   that mean it’s older version of the script? Google is making many changes in 
   Chrome lately. I am just afraid some day it will just stop working, if the script
   uses older versions. Is that a valid concern?
 *  Plugin Author [Jordy Meow](https://wordpress.org/support/users/tigroumeow/)
 * (@tigroumeow)
 * [5 years, 6 months ago](https://wordpress.org/support/topic/avoid-serving-legacy-javascript-to-modern-browsers/#post-13663404)
 * Hi,
 * Don’t worry at all 🙂 That’s totally fine. I am not sure why it’s marked as legacy
   JS, because is certainly isn’t. But no worries, Ten of thousands (more?) people
   are using this plugin and it’s actively being developed, those librairies are
   getting updated and refreshed at every release.

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

The topic ‘Avoid serving legacy JavaScript to modern browsers’ is closed to new 
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 * 3 replies
 * 2 participants
 * Last reply from: [Jordy Meow](https://wordpress.org/support/users/tigroumeow/)
 * Last activity: [5 years, 6 months ago](https://wordpress.org/support/topic/avoid-serving-legacy-javascript-to-modern-browsers/#post-13663404)
 * Status: resolved