I'm a student learning in javascript and I'm trying to build a search function.
I have multiple html figure with pictures. I'm filtering the figures with a input and with the figcaptions.
I'm trying to hide the figures that don't match with value that is put into the input.
But I have a figure that already has a css display:none;.
And when you search for this certain figure it pops up but after the input is empty again the figure stays visible.
I tried to reset the css by using obj.style.display = "" and obj.style.display = "none". But that didn't work.
Briefly my goal is to hide a figure until it matches the value of input, but if input is empty it should be hidden again.
Any help would be appreciated, thank you!

// entire code can be found here: https://codepen.io/Yung_n-d/pen/mdwQGqX
//Javascript
function myFunction() {
    var input, filter, ul, li, a, i, txtValue, getSpecial;
    input = document.getElementById("myInput");
    filter = input.value.toUpperCase();
    ul = document.getElementById("background");
    li = ul.getElementsByTagName("figure");
    getSpecial = document.getElementsByClassName('special');
 
    for (i = 0; i < li.length; i++) {

        a = li[i].getElementsByTagName("figcaption")[0];
        txtValue = a.textContent || a.innerText;


        if (txtValue.toUpperCase().indexOf(filter) > -1 ) {

            li[i].style.display = "";
            
        } else {
            li[i].style.display = "none";
            
        }
        if(filter == 0){
          getSpecial.style.display = "";
          
        }
    }
} 

//HTML
<input type="text" id="myInput" onkeyup="myFunction()" placeholder="Zoek workshops.." title="Type in a name">
<div id="background">
  <div id="gallery">
    <figure class="pic1 4-5 6-8 8-12 12+ Dans">
      <a href="workshopPages/dans/index.php">
      <img src="media/fotos/gallery/Dans.png" />
      <figcaption class="test">Dans</figcaption>
    </figure>
    <figure class="special" style="display: none;" id="8-12" class="pic10 4-5 6-8 8-12 12+ ckv">
      <a href="workshopPages/reeks/index.php">
      <img src="media/fotos/gallery/reeks.png" />
      <figcaption>Film</figcaption>
    </figure>
  </div>
</div>