diff --git a/sunpy/node/nodes/swapnode.js b/sunpy/node/nodes/swapnode.js
index d698447..82aa5c8 100644
--- a/sunpy/node/nodes/swapnode.js
+++ b/sunpy/node/nodes/swapnode.js
@@ -16,6 +16,12 @@ export class SwapNode extends BaseNode {
if (this.hasReplaceNodes)
return false;
+ // Copy id and classes to new node
+ if (this.node.id)
+ this.swapNode.id = this.node.id;
+ if (this.node.classList.length)
+ this.swapNode.classList = this.node.classList;
+
this.linker(this.node, this.swapNode);
this.node.parentNode.replaceChild(this.swapNode, this.node);
diff --git a/tests/init.html b/tests/init.html
index 5cd3603..d64ae1b 100644
--- a/tests/init.html
+++ b/tests/init.html
@@ -21,10 +21,10 @@
-
-