How to send JSON data to HTML Component?

Hi, I am stuck at a problem, where I want to query a database then send the res.items to the HTML Component. But I don’t know how to send json to the component?

This is the code I have written:

table_Data() // A backend function that gives me the json data;
    .then((data) => {
        console.log(data)
        $w("#html3").postMessage(data);
    })

HTML Code -

<html>
<body>
 <div id="output" style="background-color: aliceblue;"></div> 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
 <script src="https://cdnjs.cloudflare.com/ajax/libs/pivottable/2.23.0/pivot.min.js"></script>
 <script src="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"></script>
 
 <script>

                    let receivedData;

                    window.onmessage = (event) => {
                                       if (event.data) {
                                                          receivedData = event.data;
                                                          console.log(receivedData)
                                                          $("#output").pivot(
                                                                             receivedData,
                                                                             {
                                                                                                rows: ["Frame No"],
                                                                                                cols: ["Engine No"]
                                                                             }
                                                          );
                                       }
                       }
 </script>
</body>
</html>

table_Data () // A backend function that gives me the json data;
. then (( data ) => {
console . log ( data1 )
$w ( “#html3” ). postMessage ( data1 );
})

The parameter is data (from then() and not data1.

{Code Updated}

That was a misprinting here, I have changed.