secure-sharing/SecureSharing/Views/Home/LinkEdit.cshtml

@{
    Layout = "~/Views/Shared/_Layout.cshtml";
}
@model MessageModel

<h1>@Model.Id</h1>
<h1>@Model.Code</h1>

<h1>Share files</h1>
<form method="post" enctype="multipart/form-data" asp-controller="Home" asp-action="UpdateMessage" class="share-files-form">
    <input type="hidden" asp-for="Id" value="@Model.Id">
    <input type="hidden" asp-for="Code" value="@Model.Code">
    <div class="mb-3">
        <label class="label-text">Message (optional)</label>
        <textarea asp-for="Text" class="input-message"></textarea>
    </div>
    <div class="mb-3">
        <label class="label-text">Upload files</label>
        <div id="dropContainer" class="drop-here">
            <img class="image-file-upload" src="~/img/file-upload-image.png" alt=""/>
            <div class="default-text text-files-upload">
                <label for="fileInput" class="btn browse-button">
                    <span style="color:#0D1C52">Drag and drop files here or</span> browse
                </label>
                <input asp-for="Files" id="fileInput" type="file" multiple style="display: none"/>
                <input asp-for="FilesAsText" id="fileInputAsText" type="text" style="display:none" value="978682e8-3ce7-4258-b731-d027b5b213aa"/>
            </div>
        </div>
    </div>

    <div class="mb-3">
        <div class="label-text">
            Your files
        </div>
        <div id="filesUploaded">
        </div>
    </div>
    <button class="btn btn-light share-button" type="submit">Save</button>
</form>

<script src="~/plugins/jquery/jquery.js" type="text/javascript"></script>
<script type="text/javascript">
var filesUploaded = document.getElementById("filesUploaded");
$('#fileInput').change(function() {
  var files = $('#fileInput')[0].files

  for (var i = 0; i < files.length; i++){
    filesUploaded.innerHTML +='<p>' +  files[i].name + '</p>';
  }
});

var selectedFiles;

$(document).ready(() => {
  var box;
  box = document.getElementById("dropContainer");
  box.addEventListener("dragenter", OnDragEnter, false);
  box.addEventListener("dragover", OnDragOver, false);
  box.addEventListener("drop", OnDrop, false);
})

function OnDragEnter(e) {
  e.stopPropagation();
  e.preventDefault();
}

function OnDragOver(e) {
  e.stopPropagation();
  e.preventDefault();
}

function OnDrop(e) {
  e.stopPropagation();
  e.preventDefault();
  var selectedFiles = e.dataTransfer.files;
  var formData = new FormData();
  var fileInput = document.getElementById("fileInputAsText");
  
  for (var i = 0; i < selectedFiles.length; i++){
    formData.append(selectedFiles[i].name, selectedFiles[i]);
  }
  
  $.ajax({  
    url: '/Home/UploadTemporaryFile',  
    type: "POST",  
    contentType: false,
    processData: false, 
    data: formData,  
    success: function (result) {  
        for (var i = 0; i < selectedFiles.length; i++){
            fileInput.value += result + ':' + selectedFiles[i].name + ';';
            filesUploaded.innerHTML += '<p>' +  selectedFiles[i].name + '</p>';
        }        
    },  
    error: function (err) {  
        console.log(err)
    }  
  });  
}
</script>