title: Blob object to base64 in JavaScript
body: <p>I am trying to implement a paste handler to get an image from user's clipboard. I want this to run only on Google Chrome, I am not worried with other browsers.</p>
  
  <p>This is a part of a method that I found on Internet and I am trying to adapt it.</p>
  
  <pre><code>// Get the items from the clipboard
  var items = e.clipboardData.items;
      if (items) {
      // Loop through all items, looking for any kind of image
          for (var i = 0; i &lt; items.length; i++) {
              if (items[i].type.indexOf("image") !== -1) {
                  // We need to represent the image as a file,
                  var blob = items[i].getAsFile();
                  // and use a URL or webkitURL (whichever is available to the browser)
                  // to create a temporary URL to the object
                  var URLObj = window.URL || window.webkitURL;
                  var source = URLObj.createObjectURL(blob);
                  createImage(source);
                  }
              }
          }
  </code></pre>
  
  <p>The method works and I can show the image if I use my "source" as the src of a image object. The problem is that the image source in google chrome will be something like this: <code>blob:http://localhost:8080/d1328e65-ade2-45b3-a814-107cc2842ef9</code></p>
  
  <p>I need to send this image to the server, so I want to convert it to a base64 version. For example:   </p>
  
  <pre><code>data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAArgAAAAjCAIAAADwnO7RAAAKMWlDQ1BJQ0MgUHJvZmlsZQAASImdlndUU9kWh8+9N71QkhCKlNBraFICSA29SJEuKjEJEErAkAAiNkRUcERRkaYIMijggKNDkbEiioUBUbHrBBlE1HFwFBuWSWStGd+8ee/Nm98f935rn73P3Wfvfda6AJD8gwXCTFgJgAyhWBTh58WIjYtnYAcBDPAAA2wA4HCzs0IW+EYCmQJ82IxsmRP4F726DiD5+yrTP4zBAP+flLlZIjEAUJiM5/L42VwZF8k4PVecJbdPyZi2NE3OMErOIlmCMlaTc/IsW3z2mWUPOfMyhDwZy3PO4mXw5Nwn4405Er6MkWAZF+cI+LkyviZjg3RJhkDGb+SxGXxONgAoktwu5nNTZGwtY5IoMoIt43kA4EjJX/DSL1jMzxPLD8XOzFouEiSniBkmXFOGjZMTi+HPz03ni8XM...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
  </code></pre>
  
  <p>In the first piece of code I have a blob object representing the file. I have tried a couple of methods but I am not getting the correct representation. How I can use it to create a base64 representation? </p>