You need to modify the following code:

$('.hasemoji', 'body').each(function(e) {

To something like this:

$('.bx-base-text-entity-content', 'body').each(function(e) {

To make it works in Posts, Discussions modules. For other modules different selector is required.

Also js file can be uploaded into Studio > Storage, then you can insert this code into Studio > Designer > Injections > HEAD.