Tool collection to use with mjs (Mongoose-OS JavaScript)

tools.js

/** 
  Copyright 2018 M.Mueller-Spaeth <[email protected]>
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY
  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**/

// Simple mjs solution to split string into an array
function splitString(inTxt, sepChr) {
  let pos = inTxt.indexOf(sepChr);
  let out = [];
  let part = '';
  while (pos !== -1) {
    part = inTxt.slice(0, pos);
    if (part.length > 0) out.push(part);inTxt = inTxt.slice(pos+1, inTxt.length);
		pos = inTxt.indexOf(sepChr);
	}
	out.push(inTxt);
	return out;
}

inTxt = inTxt.slice(pos+1, inTxt.length);
this line return null string sometime and sometime its working fine.