With highlight.js, SpecialChars will disappear after creation (perhaps to do with SelectTokenCallbacks)

[WebCoder49]

Using these special characters (all ASCII chars from 0000 to 007F), on Firefox 140:

�������� � ������������������ !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~�

Out of the full-plugin demos here, only with highlight.js and not with Prism.js, selecting text in the <textarea> or pressing arrow keys (but not adding/deleting text which changes the value and causes a rehighlight) causes:

• the special characters to disappear and stop taking up space in the highlighted element.
• This is a vague description and the characters disappear at some other times, too, but with little pattern; sometimes some but not all of the characters disappear.
• This may be to do with SelectTokenCallbacks, since inspecting the element shows code-input_select-token-callbacks_temporary-span elements in the highlighted element.