text: let input = document.querySelector(".form input");
  let button = document.querySelector(".form button");
  let qrImg = document.querySelector(".qr-img img");
  
  button.addEventListener("click", function() {
      let data = input.value;
      if (data.length > 0) {
          let imgSrc = "http://api.qrserver.com/v1/create-qr-code/?size=400x400&data=" + data;
          qrImg.src = imgSrc;
      }
  });