binary encoding regex

function solve() {
  //TODO...
  let text=document.getElementById("str").value;
  let elementsToRemove=text.split("")
  .map(Number)
  .reduce((a,b)=>{return a+b})
  .toString()
  .split('')
  .map(Number)
  .reduce(function (a, b) {
      return a + b;
  }, 0);
  let pattern = /[A-Za-z\s]/;
  while (elementsToRemove > 9) {
    elementsToRemove = +(String(elementsToRemove).split('').reduce((a, b) => +a + +b));
  }
  let lastIndex=text.length-elementsToRemove;
  let textToConvert=text.substring(elementsToRemove,lastIndex);
  let convert=textToConvert.match(/(.{1,8})/g)
  .map(el => parseInt(el, 2))
  .map(el => String.fromCharCode(el))
  .join('').replace(/[^A-Za-z\s]/g,'');

  let resultDiv=document.getElementById("result");
  resultDiv.textContent=convert;
  document.getElementById("str").value="";
}