<script>
var div = document.getElementById("div");
var sel = window.getSelection();
-sel.setPosition(div, 0);
+sel.collapse(div, 0);
document.execCommand("InsertText", false, "Hello");
-sel.setPosition(div, div.childNodes.length);
+sel.collapse(div, div.childNodes.length);
document.execCommand("InsertText", false, "World");
</script>