Conversion to Extends Script from FrameScript

Hi, I want to convert my frameScript code into extends script. And as we know in frameScript most of the functions are predefined and i am not able to find the alternate of those function in ExtendScript
Please find my frameScript below

Set PlatformEncodingMode = True;

Set Displaying = 0;

Execute Fc KbdMinimize;

Set gvBookName       = Arg1;

Set gvMarkerFileName = Arg2;

Open Book File (gvBookName) NewVar(bookobj)

               BookIsInUse(ResetLockAndContinue)    

               FileIsInUse(ResetLockAndContinue)

               RefFileNotFound(Cancel)

               UpdateXRefs(No)

               ReturnFilename(returnFilename)

               FontNotFoundInDoc (OK)

               FileIsOldVersion (OK)

               AlertUserAboutFailure(False);

    Set ActiveBook = bookobj;

    write console 'book path'+returnFilename;

   Run eSys.ExtractPathName FullPath(returnFilename) NewVar(Pathname);

    Open Document File (Pathname+'2.CompilerProfile.fm') NewVar(docobj)

                       BookIsInUse(ResetLockAndContinue)    

                       FileIsInUse(ResetLockAndContinue)

                       RefFileNotFound(Cancel)

                       UpdateXRefs(No)

                       ReturnStatus(gvErrorList)

                       FontNotFoundInDoc (OK)

                       FileIsOldVersion (OK)

                       AlertUserAboutFailure(False);

    If ErrorCode = 0

       eStr.SaveToTextFile{' ', gvMarkerFileName};

        Set vDoc = ActiveDoc;

        Set vMarker = vDoc.FirstMarkerInDoc;

        Loop While (vMarker)

            If vMarker.MarkerTypeId.InvariantName = 'AutoEdoc'

                Find String ('ds2mif') InString(vMarker.MarkerText) ReturnStatus(gvfound);

                If gvFound = 1

                    Set tmp = eStr.ReplaceAll{vMarker.MarkerText, 'CR LF', ''};

                    Set vMarkerText = '{' + tmp  + '} ';

                    Write Console 'The current marker is '+vMarkerText;

                    Set gvIntVal = eStr.SaveToTextFile{vMarkerText, gvMarkerFileName, 'APPEND'};

                EndIf

            EndIf

            Set vMarker = vMarker.NextMarkerInDoc;

        EndLoop

        Close Document DocObject(docobj) IgnoreMods;

   EndIf

Close Book BookObject(bookobj) IgnoreMods;

Quit Session;

The highlighted texts are the built-in function in FrameScript my question is are the same in extendScript as well?

I am very new at extendScript. Can anyone suggest me how can I write this script into ExtendScript?

Also, anyone has any study material in this please share it with me at my email: manish13102373@gmail.com.

Thanks,
Manish