iframe-test.html

<html>
    <body>
        <button onclick="myFunction('John')">Click me</button>
        <iframe id="iframeId" 
        src="https://geojson.thelocationapi.com/#disablerecover=true&hideeditor=true&editable=false" 
        
        width="100%" height="100%"></iframe>
        <script>
            function myFunction(name) {
                //get an example polygon of a geojson object
                let geojsonExample ={
                    type:"Feature",
                    properties: {
                        name: "Coors Field",
                        amenity: "Baseball Stadium",
                        popupContent: "This is where the Rockies play!"
                    },
                    geometry: {
                        type: "Point",
                        coordinates: [-104.99404, 39.75621]
                    }
                };

                //example geojson geometry with type polygon
                const polygon = {
                    type: "Polygon",
                    coordinates: [
                        [
                            [-104.05, 39.76],
                            [-104.05, 39.79],
                            [-104.03, 39.79],
                            [-104.03, 39.76],
                            [-104.05, 39.76]
                        ]
                    ]
                };
                geojsonExample.geometry = polygon;
                var o = document.getElementsByTagName('iframe')[0];
o.contentWindow.postMessage(JSON.stringify(geojsonExample),'*');
            }
        </script>
</html>