What is the function to get the object of a NXT asset in javascript?
You can get most of the nxt objects using NRS.sendRequest(""

The following code gets the asset object of whats in question.

NRS.sendRequest("getAsset", {"asset": asset}, function(response) { //do stuff with response}, false)

NRS.sendRequest("getAsset", {   
  "asset": &lt;*Your Asset ID here*&gt;
}, function(response) {         
  if (response &amp;&amp; response.asset) {
    console.log(response);        
  }, false                          
});                             


You would get the following response from chrome's console log like this:

http://prntscr.com/7zm5fh