Пример кода (набрано, не проверено):
<textarea id="input"></textarea>
<button onclick="fPreview()">preview</button>
<div id="output"></div>
<script type="text/javascript">
function fPreview() {
var oInput = document.getElementById("input");
var oOutput = document.getElementById("output");
// clean preview area
if (oOutput.firstChild)
oOutput.removeChild(oOutput.firstChild);
// parse text into DOM and show it in preview
var oSVGInput = new DOMParser().parseFromString(oInput.value, "text/xml");
if (oSVGInput.documentElement)
oOutput.appendChild(document.importNode(oSVGInput.documentElement));
else
oOutput.appendChild("Unknown error");
}
</script>