From c432f8a1d790ab4ab1f5eb2816480d587d3874bb Mon Sep 17 00:00:00 2001
From: nojaf <florian.verdonck@outlook.com>
Date: Sat, 1 Mar 2025 14:22:50 +0100
Subject: [PATCH] Prototype type safe query selector

---
 src/DOMAPI/Document.js               | 11 +++++++++++
 src/DOMAPI/Document.res              | 11 +++++++++++
 src/DOMAPI/HTMLHeadingElement.js     | 15 +++++++++++++++
 src/DOMAPI/HTMLHeadingElement.res    |  9 +++++++++
 tests/DOMAPI/QuerySelector__test.js  | 15 +++++++++++++++
 tests/DOMAPI/QuerySelector__test.res | 14 ++++++++++++++
 6 files changed, 75 insertions(+)
 create mode 100644 tests/DOMAPI/QuerySelector__test.js
 create mode 100644 tests/DOMAPI/QuerySelector__test.res

diff --git a/src/DOMAPI/Document.js b/src/DOMAPI/Document.js
index eee8545..0c57006 100644
--- a/src/DOMAPI/Document.js
+++ b/src/DOMAPI/Document.js
@@ -1,14 +1,25 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as Node$WebAPI from "./Node.js";
+import * as HTMLHeadingElement$WebAPI from "./HTMLHeadingElement.js";
 
 Node$WebAPI.Impl({});
 
+function querySelectorAsHeading(document, selector) {
+  let element = document.querySelector(selector);
+  if (element === null || !HTMLHeadingElement$WebAPI.isInstanceOf(element)) {
+    return;
+  } else {
+    return element;
+  }
+}
+
 function isInstanceOf(param) {
   return (param instanceof Document);
 }
 
 export {
+  querySelectorAsHeading,
   isInstanceOf,
 }
 /*  Not a pure module */
diff --git a/src/DOMAPI/Document.res b/src/DOMAPI/Document.res
index 60cef5b..c772d17 100644
--- a/src/DOMAPI/Document.res
+++ b/src/DOMAPI/Document.res
@@ -86,6 +86,17 @@ Returns the first element that is a descendant of node that matches selectors.
 @send
 external querySelector: (document, string) => Null.t<element> = "querySelector"
 
+/**
+Invoke querySelector and checks if the element is an HTMLHeadingElement.
+[Read more on MDN](https://developer.mozilla.org/docs/Web/API/Document/querySelector)
+*/
+let querySelectorAsHeading = (document, selector): option<htmlHeadingElement> => {
+  switch querySelector(document, selector) {
+  | Value(element) if HTMLHeadingElement.isInstanceOf(element) => Some(element->Obj.magic)
+  | _ => None
+  }
+}
+
 /**
 Returns all element descendants of node that match selectors.
 [Read more on MDN](https://developer.mozilla.org/docs/Web/API/Document/querySelectorAll)
diff --git a/src/DOMAPI/HTMLHeadingElement.js b/src/DOMAPI/HTMLHeadingElement.js
index 1541b40..56eb206 100644
--- a/src/DOMAPI/HTMLHeadingElement.js
+++ b/src/DOMAPI/HTMLHeadingElement.js
@@ -4,4 +4,19 @@ import * as HTMLElement$WebAPI from "./HTMLElement.js";
 
 HTMLElement$WebAPI.Impl({});
 
+function isInstanceOf(param) {
+  return (param instanceof HTMLHeadingElement);
+}
+
+function tryParse(element) {
+  if (isInstanceOf(element)) {
+    return element;
+  }
+  
+}
+
+export {
+  isInstanceOf,
+  tryParse,
+}
 /*  Not a pure module */
diff --git a/src/DOMAPI/HTMLHeadingElement.res b/src/DOMAPI/HTMLHeadingElement.res
index 6fc967a..7b50586 100644
--- a/src/DOMAPI/HTMLHeadingElement.res
+++ b/src/DOMAPI/HTMLHeadingElement.res
@@ -3,3 +3,12 @@ open DOMAPI
 include HTMLElement.Impl({
   type t = htmlHeadingElement
 })
+
+let isInstanceOf = (_: 't): bool => %raw(`param instanceof HTMLHeadingElement`)
+
+let tryParse = (element: 't): option<htmlHeadingElement> =>
+  if isInstanceOf(element) {
+    Some(element->Obj.magic)
+  } else {
+    None
+  }
diff --git a/tests/DOMAPI/QuerySelector__test.js b/tests/DOMAPI/QuerySelector__test.js
new file mode 100644
index 0000000..bc00006
--- /dev/null
+++ b/tests/DOMAPI/QuerySelector__test.js
@@ -0,0 +1,15 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Stdlib_Option from "rescript/lib/es6/Stdlib_Option.js";
+import * as Document$WebAPI from "../../src/DOMAPI/Document.js";
+import * as HTMLHeadingElement$WebAPI from "../../src/DOMAPI/HTMLHeadingElement.js";
+
+Stdlib_Option.forEach(Document$WebAPI.querySelectorAsHeading(document, "h2"), heading => {
+  heading.style.color = "red";
+});
+
+Stdlib_Option.forEach(Stdlib_Option.flatMap(Document$WebAPI.querySelectorAsHeading(document, "h2"), HTMLHeadingElement$WebAPI.tryParse), heading => {
+  heading.style.color = "red";
+});
+
+/*  Not a pure module */
diff --git a/tests/DOMAPI/QuerySelector__test.res b/tests/DOMAPI/QuerySelector__test.res
new file mode 100644
index 0000000..2f5fada
--- /dev/null
+++ b/tests/DOMAPI/QuerySelector__test.res
@@ -0,0 +1,14 @@
+// Option 1
+Global.document
+->Document.querySelectorAsHeading("h2")
+->Option.forEach(heading => {
+  heading.style.color = "red"
+})
+
+// Option 2
+Global.document
+->Document.querySelectorAsHeading("h2")
+->Option.flatMap(HTMLHeadingElement.tryParse)
+->Option.forEach(heading => {
+  heading.style.color = "red"
+})