// fill the element selector before run
let elementInterval;
let elementDefined = false
function modifyElement(elementSelector) {
  const optionContainer = document.querySelector(elementSelector);

  if (!optionContainer) {
    return null
  }

  const subTitle = document.createElement('p');
  subTitle.innerHTML = `TEST`
  optionContainer.appendChild(subTitle)
  
  elementDefined = true
  if(elementInterval) {
    clearInterval(elementInterval)
  }

}

if (!elementInterval) {
  elementInterval = setInterval(modifyElement(elementSelector), 50)
}