pasteFromClipboard.js

document.onpaste = function(event){
  var items = (event.clipboardData || event.originalEvent.clipboardData).items;
  console.log(JSON.stringify(items)); // will give you the mime types
  var blob = items[0].getAsFile();
  var reader = new FileReader();
  reader.onload = function(event){
    console.log(event.target.result)}; // data url!
  reader.readAsDataURL(blob);
}