How to Create Shortener URL in Google API using JavaScript

<script type="text/javascript">
   function makeShort()
   {
      var longUrl=document.getElementById("longurl").value;
      var request = gapi.client.urlshortener.url.insert({
         'resource': {
            'longUrl': longUrl
            }
         });
         request.execute(function(response)
         {
            if(response.id != null)
            {
               str ="<b>Long URL:</b>"+longUrl+"<br>";
               str +="<b>Short URL:</b> <a href='"+response.id+"'>"+response.id+"</a><br>";
               document.getElementById("output").innerHTML = str;
            }
            else
            {
               alert("error: creating short url \n"+ response.error);
           }
         });
      }
      function getShortInfo()
      {
         var shortUrl=document.getElementById("shorturl").value;
         var request = gapi.client.urlshortener.url.get({
         'shortUrl': shortUrl,
         'projection':'FULL'
      });
      request.execute(function(response)
      {
         if(response.longUrl!= null)
         {
            str ="<b>Long URL:</b>"+response.longUrl+"<br>";
            str +="<b>Create On:</b>"+response.created+"<br>";
            str +="<b>Short URL Clicks:</b>"+response.analytics.allTime.shortUrlClicks+"<br>";
            str +="<b>Long URL Clicks:</b>"+response.analytics.allTime.longUrlClicks+"<br>";
            document.getElementById("output").innerHTML = str;
         }
         else
         {
            alert("error: "+response.error);
         }
      });
   }
   function load()
   {
      //Get your own Browser API Key from https://code.google.com/apis/console/
      gapi.client.setApiKey('your-api-key');
      gapi.client.load('urlshortener', 'v1',function(){document.getElementById("output").innerHTML="";});
   }
   window.onload = load;
</script>
<script src="https://apis.google.com/js/client.js"> </script>
   <body>
      <h1> Google URL Shortener API Demo </h1>
         <table>
            <tr>
               <td>
                  URL: <input type="text" id="longurl" name="url" size=30 value="" /> <br/>
                  <input type="button" value="Create Short" onClick="makeShort();" /> <br/> <br/>
                  URL: <input type="text" id="shorturl" name="url" value="" /> <br/>
                  <input type="button" value="Get Short URL Info" onClick="getShortInfo();" />
               </td>
            <td>
            <div id="output"></div>
         </td>
      </tr>
</table>