Self closing xml elements considered harmful

[K.Daube]

Dear friends, experts and gurus!

Main purpose of my project FMfindRepl is saving the settings to an xml file and get them back later.

It turns out that 'roung-tripping' empty edit-fields is not handled correctly. It even leads to blocked functions (Buttons will not work any more).

• Field "find what" is empty for various find operations, for example when searching for Anchored Frames. This is represented in the xml file as

 <findstring></findstring>​

• At the next start of FM with the script  things work as expected.
• As long as I do not save a new set of settings nothing strange happens and the next FM session is OK.
• Saving new settings of course recreates the xml file. And now the previously existing 

<findstring></findstring>​

are saved to the file as

 <findstring/>​

• This is absolutely correct in the sense of XM, but ...
• ... in the next FM session these empty elements create problems. There is no more a distinction between an empty string, a null or undefined element. See my  test script (after dl rename *.txt to *.jsx).

A crunch would be to postprocess the written xml file and replace all self-terminated elements by ordinary elements with start and end tags (see stackexchange).

<(\w+)/>       →     <$1></$1>

But I want to avoid writing these self-terminated elements directly.

→ How could this be achieved?

[K.Daube · Accepted solution]

For the time being I decided to modifiy the written xml file with a function:

KLD_F.ConvertSelfTerminatedElements = function (xFile) { // ==========================
/*            Expand self-terminating xml elements to empty start-tag end-tag elements
Arguments     xFile           xml file to be modified
Returns       false in case of error, else true
Called by     ButtonDelete, ButtonSave, ButtonSaveNew
Comment       Self-terminating xml elements create problems when they are read. 
              Buttons Retrieve, Save, SaveNew, Delete and Reset do not work any more.
Reference     https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace
Used in       FMfindRepl
History       2021-03-22
*/
var BOM = "\uFEFF", eReg1, eReg2, fXFile, xData;

function replacer (match, p1) {
  return "<" + p1 + "></" + p1 + ">";
}

  if ((xFile == null) || (xFile == undefined)) {
    return false;
  } else if (xFile.indexOf("/") > 0 || xFile.indexOf("\\") > 0) { // fully qualified path
    fXFile = new File(xFile);
  } else {
    fXFile = new File($.fileName.replace (/[^\\\/]+$/i , xFile));  // file in script folder
  }
  if (fXFile.exists === false) {
    KLD_F.Message ("E", KLD_F.UItxt.ConvertSelfTerminatedElements.@msg_01, "ConvertSelfTerminatedElements", sXmlFile, e.message);
      return false;
  }
  fXFile.open("r");
  xData = fXFile.read();
  fXFile.close ();
  xData = xData.replace (/<(\w+)\/>/g , replacer);
  fXFile.open('w');
  fXFile.encoding = "UTF-8";
  fXFile.write(BOM);
  fXFile.write(xData);
  fXFile.close();

  return true;
} //--- end ExpandSelfTerminatedElements -------------------------------------