Upload image summernote editor to Azure Storage

When you upload an image to Summernote editor, it will convert the image to base64 data. And base64 is larger than the original data size. So in this post, I will explain how to upload the picture to Azure Storage instead of converting to base64.

Very roughly, the final size of Base64-encoded binary data is equal to 1.37 times the original data size + 814 bytes (for headers). Wikipedia


Install and setup the Azure Storage.


Create a controller to upload the picture to Azure Storage. It's simply get the request file, upload, that's it.

public class SummernoteController : Controller
    private readonly IAzureFileUploaderService _azureFileUploaderService;

    public SummernoteController(IAzureFileUploaderService azureFileUploaderService)
        _azureFileUploaderService = azureFileUploaderService;

    public async Task<ActionResult> ImageUpload()
        var files = Request.Files;
        var url = string.Empty;
        if (files.Count > 0)
            url = await _azureFileUploaderService.UploadPhotoAsync(files[0], Global.Full, "summernote");
        return Json(url);


We'll be using onImageUpload from summernote. Documentation

    height: 200,
    onImageUpload: function (files) {
        sendFile(files[0], this);

The el parameter is basically the summernote DOM element. We need this to update the insert the uploaded picture from Azure Storage.

function sendFile(file, el) {
    var formdata = new FormData();
    formdata.append(file.name, file);
    var xhr = new XMLHttpRequest();
    xhr.open('POST', '/summernote/ImageUpload/');
    xhr.onreadystatechange = function () {
        if (xhr.readyState == 4 && xhr.status == 200) {
            var response = xhr.response.replace(new RegExp('"', 'g'), '');
            $(el).summernote('insertImage', response, file.name);
    return false;

First, we create a FormData object, append the file, post an http post request to the controller we created above. When it's done, call insertImage. Documentation

Done! :)