#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?i)(className|class)="(?:block|block\s([^"]*)|([^"]*)\sblock|([^"]*)\sblock(?=\s)([^"]*))""
Local $sString = "class="block underline primary blockOverlay"" & @CRLF & _
"" & @CRLF & _
"class="name block"" & @CRLF & _
"" & @CRLF & _
"class="block name"" & @CRLF & _
"" & @CRLF & _
"className="text-center block primary-dark blockout__form"" & @CRLF & _
"" & @CRLF & _
"class="grey bg-black inline-block block blocktitle blockouts-intro"" & @CRLF & _
"" & @CRLF & _
"class="grey bg-black inline-block block-title blockouts-intro"" & @CRLF & _
"" & @CRLF & _
"class="grey bg-black inline-block block title-block blockouts-intro"" & @CRLF & _
"" & @CRLF & _
"class="block""
Local $sSubst = "\1="\2\3\4\5""
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