input file to array javascript/jquery

Edit, Updated

how can i delete a specific item in upload variable?

If expected result is array of file objects would adjust approach to splicing array items from original files object – and sending spliced array as upload – instead of attempting to “delete” items from original files object and still uploading original files object.

FileList object does not have .splice() method . Try utilizing .slice() , .call() to convert files to Array , then call .splice() method on array of File objects, e.g.;

// `_files` : `File` object items from original `files` `FileList`
// call `.splice()` on items that would be uploaded ,
// upload `_files` array - _not_ original `files` `FileList` object
// e.g.; `_files`:`File` objects to _keep_ not "delete" from `files`
var idstokeep = [0, 2]; // splice , keep first `2` files 
var _files = Array.prototype.slice.call(files).splice(idstokeep[0], idstokeep[1]);

See how does Array.prototype.slice.call() work?

Alternatively , utilize

item()

Returns a File object representing the file at the
specified index in the file list.

to return files at specific index within FileList

  var files = e.target.files;
  // return `file` at `index` `1`
  var firstFile = files.item(1);

var upload = document.getElementById("file1");

upload.onchange = function(e) {
  var files = e.target.files;
  // https://developer.mozilla.org/en-US/docs/Web/API/FileList#item
  var firstFile = files.item(1); 
  var idstokeep = [0, 2]; // keep first `2` files from `multiple` selection
  var _files = Array.prototype.slice.call(files).splice(idstokeep[0], idstokeep[1]);
  console.log(files, files.length         
              , _files, _files.length
              , firstFile);
};

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js">
</script>
<input class="file" id="file1" name="uploadedimages[]" type="file" multiple/>