DOM: CEReactions vs script during insertion

Complements #15264.

dom/nodes/Node-appendChild-cereactions-vs-script.window.js

@@ -0,0 +1,27 @@
+const results = [];
+test(() => {
+ class Script1 extends HTMLScriptElement {
+ constructor() {
+ super();
+ }
+ connectedCallback() {
+ results.push("ce connected s1");
+ }
+ }
+ class Script2 extends HTMLScriptElement {
+ constructor() {
+ super();
+ }
+ connectedCallback() {
+ results.push("ce connected s2");
+ }
+ }
+ customElements.define("script-1", Script1, { extends: "script" });
+ customElements.define("script-2", Script2, { extends: "script" });
+ const s1 = new Script1();
+ s1.textContent = "results.push('s1')";
+ const s2 = new Script2();
+ s2.textContent = "results.push('s2')";
+ document.body.append(s1, s2);
+ assert_array_equals(results, ["s1", "s2", "ce connected s1", "ce connected s2"]);
+}, "Custom element reactions follow script execution");