Сохранение положения выбранного option в разных select

$('select').on('change', function(){ 
	let selClass = $(this).attr('class'), 
  		optVal = $(this).val(); 
  $('.'+selClass).val(optVal); 
	checkSelect($(this),optVal,selClass); 
}); 
 
function checkSelect(elem,elemValue,elemClass) { 
	let el = JSON.parse(localStorage.getItem('select')); 
  let obj = {class:elemClass,value:elemValue}; 
	if (elemValue != '-1' && el != null) {  
    let id = null; 
    $(el).each(function(key,elem){ 
      if (elem.class == elemClass) { 
      	id = key; 
      } 
    }); 
    if (id!=null) { 
    	el[id] = obj; 
    } else { 
    	el.push(obj); 
    } 
    localStorage.setItem('select', JSON.stringify(el)); 
  } else { 
  	localStorage.setItem('select', JSON.stringify([obj])); 
  } 
} 
 
$(function(){ 
	let elems = JSON.parse(localStorage.getItem('select')); 
  if (elems!=null) { 
    $(elems).each(function(key,elem){ 
  	  $('.'+elem.class).val(elem.value); 
    }); 
  } 
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> 
<select class="s1"> 
  <option value="-1" selected hidden>choose value</option> 
  <option value="s1">s1</option> 
  <option value="s2">s2</option> 
  <option value="s3">s3</option> 
</select> 
<select class="s1"> 
  <option value="-1" selected hidden>choose value</option> 
  <option value="s1">s1</option> 
  <option value="s2">s2</option> 
  <option value="s3">s3</option> 
</select> 
<select class="s2"> 
  <option value="-1" selected hidden>choose value</option> 
  <option value="s1">s1</option> 
  <option value="s2">s2</option> 
  <option value="s3">s3</option> 
</select> 
<select class="s2"> 
  <option value="-1" selected hidden>choose value</option> 
  <option value="s1">s1</option> 
  <option value="s2">s2</option> 
  <option value="s3">s3</option> 
</select> 
<select class="s3"> 
  <option value="-1" selected hidden>choose value</option> 
  <option value="s1">s1</option> 
  <option value="s2">s2</option> 
  <option value="s3">s3</option> 
</select> 
<select class="s3"> 
  <option value="-1" selected hidden>choose value</option> 
  <option value="s1">s1</option> 
  <option value="s2">s2</option> 
  <option value="s3">s3</option> 
</select>