michael@0: function test() {
michael@0:   var ids = {};
michael@0:   Array.forEach(document.querySelectorAll("[id]"), function (node) {
michael@0:     var id = node.id;
michael@0:     ok(!(id in ids), id + " should be unique");
michael@0:     ids[id] = null;
michael@0:   });
michael@0: }