<?xml version="1.0"?>
<svg version="1.1" xmlns="http://www.w3.org/2000/svg">
  <rect id="test" x="100" y="100" width="100" height="100"/>
  <script>
    window.onload = function() {
      var node = document.getElementById("test");
      node.style.width = "200px";      
    }
  </script>
</svg>