Use the element that calling eventlister inside function

How use the element that calling eventlister in a function, to append new element.

Example:

window.onload = function()
{   
    Array.from(document.getElementsByClassName('image_add_product')).forEach(function(element,index)
    {
        element.addEventListener("change", input_change, false);
    });
};

Now i need to use that element inside input_change function, to append a new element span. Using element.parentNode.insertBefore(span, this.nextSibling), get error element is not defined, using this.parentNode.insertBefore(span, this.nextSibling), get error Cannot read properties of undefined (reading 'insertBefore').

What is the correct way to do that? Pls, see the comments on code.

function input_change(evt)
{   
    //with this operator i can access the properties of element, but...       
    var file = this.files[0];
    
    if(file.size > 1572864)
    {
        console.log("Imagem exede o tamanho máximo permitido de 1,5 MB");
        this.value = "";
        return false;
    }
    var reader = new FileReader();

    reader.onload = (function(theFile)
    {   
        return function(e)
        {   
            var span = document.createElement('span');
            span.innerHTML ="<img src='...'/>";

            /*here is the problem
            how append span using element as reference*/

            this.parentNode.insertBefore(span, this.nextSibling);
        };
    })(file);
    reader.readAsDataURL(file);
    return true;
}

>Solution :

The problem is this inside the onload of the file is the file, it is NOT the this outside of it.

document.querySelectorAll('.image_add_product').forEach(function(element) {
  element.addEventListener("change", input_change, false);
});

function input_change(evt) {
  var elem = this;
  var file = elem.files[0];

  if (file.size > 1572864) {
    console.log("Imagem exede o tamanho máximo permitido de 1,5 MB");
    this.value = "";
    return false;
  }
  var reader = new FileReader();

  reader.onload = function(e) {
    var span = document.createElement('span');
    span.innerHTML = "HELLO<img src='...'/>";
    elem.parentNode.insertBefore(span, elem.nextSibling);
  };
  reader.readAsDataURL(file);
  return true;
}

<label for="img1">
  <input type="file" id="img1" class="image_add_product" >
</label>

<label for="img2">
  <input type="file" id="img2" class="image_add_product" >
</label>