#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(#table\d+)|\((\w{1,2})(\))"
Local $sString = "<p id="para"> demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test demo<a href="#table1(t1)" id="ytD2F">table1</a> test demo test demo test demo test demo test demo <a href="#table2(t2)" id="ytD2F">table2</a> demo test demo test demo test demo test demo test demo test demo test demo test demo test demo test </p>"
Local $sSubst = "$2"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm