how to upload image file from button with icon code example

Example: how to convert input type file into an icon

<div class="image-upload">
      <label for="file-input">
        <img id="previewImg" src="https://icon-library.net/images/upload-photo-icon/upload-photo-icon-21.jpg" style="width: 100px; height: 100px;" />
      </label>

      <input id="file-input" type="file" onchange="previewFile(this);" style="display: none;" />
    </div>




<script>
        function previewFile(input){
            var file = $("input[type=file]").get(0).files[0];

            if(file){
              var reader = new FileReader();

              reader.onload = function(){
                  $("#previewImg").attr("src", reader.result);
              }

              reader.readAsDataURL(file);
            }
        }
    </script>