test-js.html

<!doctype html>
<html>
<head>
	<meta charset="UTF-8">
	<title>Document sans nom</title>
 	<meta name="viewport" content="width=device-width, initial-scale=1">
	<style>
            button {
              font-size: 200%;
            }
    </style>
</head>

<body>

<object id="carte" width="400" height="300" type="image/svg+xml" data="carte1.svg"></object>

<button type="button">Click me</button>

<script>
	

	var button = document.querySelector("button");

  button.addEventListener("click", animate);


  function animate() {

    
  	var svg = document.getElementById("carte"); 
	
	var svgDoc = svg.contentDocument;

	console.log(svgDoc);
	
	var circle = svgDoc.getElementById("my-circle");

	var bordure = svgDoc.querySelector(".st0");
	
	// circle.setAttributeNS(null, "cx", 80);

	bordure.setAttribute("style", "fill: red");


  }

// 


</script>

</body>
</html>