ok... I found a simple and easy way to achive this... Simple use the "uploadData" function from BlockBlobClient with an arrayBuffer from the uploaded file :)

let formData = await req.formData();
let file = formData.get( "file" );
let buffer = file.arrayBuffer();
await blockBlobClient.uploadData( buffer );

So i can upload my files to azure blobstorage through a simple html file-form upload :)

uploadData function:

https://learn.microsoft.com/en-us/javascript/api/@azure/storage-blob/blockblobclient?view=azure-node-latest#@azure-storage-blob-blockblobclient-uploaddata