text: // ScriptHash of the contract to subscribe to
  const contractHash = "0x314b5aac1cdd01d10661b00886197f2194c3c89b";
  // Subscriptions to null are equivalent to subscribing to all the contracts
  const allContractHashes = null;
  
  // Get an instance of the Notifications server
  const provider = new Neon.api.notifications.instance("MainNet");
  
  let subscription;
  
  function InvokeSubscribeOperation()
  {
    clearHtml();
  
    // Create a subscription
    subscription = provider.subscribe(allContractHashes, (event) => {
      outputHtml('Event data: ');
      outputHtml(JSON.stringify(event, null, "  "));
    });
  }
  
  function InvokeUnsubscribeOperation()
  {
    if(subscription !== undefined){
      // Unsubscribe the previous handler
      subscription.unsubscribe();
    }
  }
  
  
  // Utility function to print output to an HTML div tag
  function outputHtml(s) {
    document.getElementById("result").innerHTML += s + "<br>";
  }
  
  function clearHtml() {
    document.getElementById("result").innerHTML = "";
  }
  