name attribute added through javascript not work

Hi,

I am using a script for input tag field https://www.cssscript.com/demo/multi-select-autocomplete-selectpure/

This script generate input field dynamically through its script and not add any name attribute by default in it.

So in my form I have added this one more line of javascript to have name attribute in its autogenerated input field.

document.querySelector(".select-pure__autocomplete").setAttribute("name", "myinputtag");

So that way now the field have name attribute in it. But when I add the shortcode [myinputtag] in the actions tab in email output message, its not sending selected tag in email (remain blank output for that field)

I am not sure where is the issue? I think this form need an input field as html with name attribute, otherwise it note take the output the field generated by JavaScript, is this true? or it is some issue at script that I am using ?