JSFiddle - React, Tailwind, and code Playground
HTML
<LI class=err_tx>
<SPAN style="DISPLAY: inline" id=rfvUrl controltovalidate="txtOkUrl" focusOnError="t" errormessage="●1234<br/>" display="Dynamic" validationGroup="ValidationProduct" initialvalue isvalid="false">
1234
<BR>
</SPAN>
<SPAN style="DISPLAY: none" id=revUrl controltovalidate="txtOkUrl" errormessage="●1234" display="Dynamic" validationGroup="ValidationProduct" validationexpression="http(s)?:([\w-]+\.)+[\w-]+(/[\w- ./?%&=]*)?$" isvalid="true">
●1234
</SPAN>
</LI>
JavaScript
alert($(".err_tx").find('span:visible').length);
alert($("<LI class=err_tx><SPAN style=\"DISPLAY: inline\" id=rfvUrl controltovalidate=\"txtOkUrl\" focusOnError=\"t\" errormessage=\"●1234<br/>\" display=\"Dynamic\" validationGroup=\"ValidationProduct\" initialvalue isvalid=\"false\">1234<BR></SPAN><SPAN style=\"DISPLAY: none\" id=revUrl controltovalidate=\"txtOkUrl\" errormessage=\"●1234\" display=\"Dynamic\" validationGroup=\"ValidationProduct\" validationexpression=\"http(s)?:([\w-]+\.)+[\w-]+(/[\w- ./?%&=]*)?$\" isvalid=\"true\">●1234</SPAN></LI>").find('span:visible').length);
alert($("<LI class=err_tx><SPAN style=\"DISPLAY: inline\" id=rfvUrl controltovalidate=\"txtOkUrl\" focusOnError=\"t\" errormessage=\"●1234<br/>\" display=\"Dynamic\" validationGroup=\"ValidationProduct\" initialvalue isvalid=\"false\">1234<BR></SPAN><SPAN style=\"DISPLAY: none\" id=revUrl controltovalidate=\"txtOkUrl\" errormessage=\"●1234\" display=\"Dynamic\" validationGroup=\"ValidationProduct\" validationexpression=\"http(s)?:([\w-]+\.)+[\w-]+(/[\w- ./?%&=]*)?$\" isvalid=\"true\">●1234</SPAN></LI>").appendTo("body").find('span:visible').length);