javascript is being called twice

I managed to get my javascript routine to run. I put the code to call it in in the _construct

$this->load->js("/js/javascript_funcs_extensionloaded.js");

The code is:

   var editorExtensionId = "lamacgnkfoiknjpleghfknfigbmhdaei";


   if (chrome && chrome.runtime && chrome.runtime.sendMessage) {
   chrome.runtime.sendMessage(extensionId, 'snapshot_mode');
}
I am finding that this code is running twice. The way I know this is that the Extension is getting the message "snapshot_mode" twice. Should I be wrapping this js code in 
$(document).ready(function(){
? Or is the problem that I am calling it in __construct()? I want the js code to run just once per initialization of my code. 

proof that an old dog can learn new tricks