function draftSave() {
  var one = ""
  document.querySelectorAll('#one > textarea').forEach(el => {
    one += el.value;
  })


  var two = ""
  document.querySelectorAll('#two > textarea').forEach(el => {
    two += el.value;
  })

  if (one !== "" && two !== "") {
    console.clear();
    console.log("alert both rows are filled")
  }else {
  console.clear();
  console.log("submited: " + one + two);
  }

}

<div id="one">row1
  <textarea rows="2" class="form-control checking-length" name="text1" id="text1" required maxlength="3500" placeholder="Your answer.."></textarea>

  <textarea rows="2" class="form-control checking-length" name="text2" id="text2" required maxlength="3500" placeholder="Your answer.."></textarea>
</div>
<div id="two">row2
  <textarea rows="2" class="form-control checking-length" name="div2_text1" id="div2_text1" required maxlength="3500" placeholder="Your answer.."></textarea>

  <textarea rows="2" class="form-control checking-length" name="div2_text2" id="div2_text2" required maxlength="3500" placeholder="Your answer.."></textarea>
</div>

<a class="btn btn-info waves-effect" name="step5" id="step5" onclick="draftSave()">Draft Save</a>

function draftSave() {
alert('hello');

}

<div id = "one">
<textarea rows="2" class="form-control checking-length" name="text1" id="text1" required maxlength="3500" onKeyup="textareacount3500_characters('text1')" placeholder="Your answer.."></textarea>

<textarea rows="2" class="form-control checking-length" name="text2" id="text2" required maxlength="3500" onKeyup="textareacount3500_characters('text2')" placeholder="Your answer.."></textarea>
</div>
<div id = "two">
<textarea rows="2" class="form-control checking-length" name="div2_text1" id="div2_text1" required maxlength="3500" onKeyup="textareacount3500_characters('div2_text1')" placeholder="Your answer.."></textarea>

<textarea rows="2" class="form-control checking-length" name="div2_text2" id="div2_text2" required maxlength="3500" onKeyup="textareacount3500_characters('div2_text2')" placeholder="Your answer.."></textarea>
</div>

<a class="btn btn-info waves-effect" name="step5" id="step5" onclick="draftSave()">Draft Save</a>