diff --git a/src/DOMAPI/Document.js b/src/DOMAPI/Document.js
index e6a3a30..eee8545 100644
--- a/src/DOMAPI/Document.js
+++ b/src/DOMAPI/Document.js
@@ -4,4 +4,11 @@ import * as Node$WebAPI from "./Node.js";
 
 Node$WebAPI.Impl({});
 
+function isInstanceOf(param) {
+  return (param instanceof Document);
+}
+
+export {
+  isInstanceOf,
+}
 /*  Not a pure module */
diff --git a/src/DOMAPI/Document.res b/src/DOMAPI/Document.res
index 946d76f..60cef5b 100644
--- a/src/DOMAPI/Document.res
+++ b/src/DOMAPI/Document.res
@@ -458,3 +458,5 @@ external hasStorageAccess: document => promise<bool> = "hasStorageAccess"
 */
 @send
 external requestStorageAccess: document => promise<unit> = "requestStorageAccess"
+
+let isInstanceOf = (_: 't): bool => %raw(`param instanceof Document`)
diff --git a/src/DOMAPI/Element.js b/src/DOMAPI/Element.js
index d7d93d7..78c6978 100644
--- a/src/DOMAPI/Element.js
+++ b/src/DOMAPI/Element.js
@@ -9,7 +9,12 @@ function Impl(T) {
 
 Node$WebAPI.Impl({});
 
+function isInstanceOf(param) {
+  return (param instanceof Element);
+}
+
 export {
   Impl,
+  isInstanceOf,
 }
 /*  Not a pure module */
diff --git a/src/DOMAPI/Element.res b/src/DOMAPI/Element.res
index 5fd2444..73860c9 100644
--- a/src/DOMAPI/Element.res
+++ b/src/DOMAPI/Element.res
@@ -498,3 +498,5 @@ Returns true if qualifiedName is now present, and false otherwise.
 include Impl({
   type t = element
 })
+
+let isInstanceOf = (_: 't): bool => %raw(`param instanceof Element`)
diff --git a/src/IntersectionObserverAPI.js b/src/IntersectionObserverAPI.js
new file mode 100644
index 0000000..d856702
--- /dev/null
+++ b/src/IntersectionObserverAPI.js
@@ -0,0 +1,2 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+/* This output is empty. Its source's type definitions, externals and/or unused code got optimized away. */
diff --git a/src/IntersectionObserverAPI.res b/src/IntersectionObserverAPI.res
new file mode 100644
index 0000000..933c425
--- /dev/null
+++ b/src/IntersectionObserverAPI.res
@@ -0,0 +1,69 @@
+@@warning("-30")
+
+open DOMAPI
+
+@editor.completeFrom(IntersectionObserverRoot)
+type root
+
+/**
+provides a way to asynchronously observe changes in the intersection of a target element with an ancestor element or with a top-level document's viewport.
+[See IntersectionObserver on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver)
+*/
+@editor.completeFrom(IntersectionObserver)
+type intersectionObserver = {
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver/root)
+    */
+  root: root,
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver/rootMargin)
+    */
+  rootMargin: string,
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver/thresholds)
+    */
+  thresholds: array<float>,
+}
+
+/**
+This Intersection Observer API interface describes the intersection between the target element and its root container at a specific moment of transition.
+[See IntersectionObserverEntry on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserverEntry)
+*/
+type intersectionObserverEntry = {
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserverEntry/time)
+    */
+  time: float,
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserverEntry/rootBounds)
+    */
+  rootBounds: Null.t<domRectReadOnly>,
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserverEntry/boundingClientRect)
+    */
+  boundingClientRect: domRectReadOnly,
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserverEntry/intersectionRect)
+    */
+  intersectionRect: domRectReadOnly,
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserverEntry/isIntersecting)
+    */
+  isIntersecting: bool,
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserverEntry/intersectionRatio)
+    */
+  intersectionRatio: float,
+  /**
+    [Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserverEntry/target)
+    */
+  target: element,
+}
+
+type intersectionObserverInit = {
+  mutable root?: root,
+  mutable rootMargin?: string,
+  mutable threshold?: array<float>,
+}
+
+type intersectionObserverCallback = (array<intersectionObserverEntry>, intersectionObserver) => unit
diff --git a/src/IntersectionObserverAPI/IntersectionObserver.js b/src/IntersectionObserverAPI/IntersectionObserver.js
new file mode 100644
index 0000000..d856702
--- /dev/null
+++ b/src/IntersectionObserverAPI/IntersectionObserver.js
@@ -0,0 +1,2 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+/* This output is empty. Its source's type definitions, externals and/or unused code got optimized away. */
diff --git a/src/IntersectionObserverAPI/IntersectionObserver.res b/src/IntersectionObserverAPI/IntersectionObserver.res
new file mode 100644
index 0000000..3ed85ed
--- /dev/null
+++ b/src/IntersectionObserverAPI/IntersectionObserver.res
@@ -0,0 +1,35 @@
+open DOMAPI
+open IntersectionObserverAPI
+
+/**
+[Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver)
+*/
+@new
+external make: (
+  ~callback: intersectionObserverCallback,
+  ~options: intersectionObserverInit=?,
+) => intersectionObserver = "IntersectionObserver"
+
+/**
+[Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver/observe)
+*/
+@send
+external observe: (intersectionObserver, element) => unit = "observe"
+
+/**
+[Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver/unobserve)
+*/
+@send
+external unobserve: (intersectionObserver, element) => unit = "unobserve"
+
+/**
+[Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver/disconnect)
+*/
+@send
+external disconnect: intersectionObserver => unit = "disconnect"
+
+/**
+[Read more on MDN](https://developer.mozilla.org/docs/Web/API/IntersectionObserver/takeRecords)
+*/
+@send
+external takeRecords: intersectionObserver => array<intersectionObserverEntry> = "takeRecords"
diff --git a/src/IntersectionObserverAPI/IntersectionObserverRoot.js b/src/IntersectionObserverAPI/IntersectionObserverRoot.js
new file mode 100644
index 0000000..5418042
--- /dev/null
+++ b/src/IntersectionObserverAPI/IntersectionObserverRoot.js
@@ -0,0 +1,25 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Element$WebAPI from "../DOMAPI/Element.js";
+import * as Document$WebAPI from "../DOMAPI/Document.js";
+
+function decode(t) {
+  if (Element$WebAPI.isInstanceOf(t)) {
+    return {
+      TAG: "Element",
+      _0: t
+    };
+  } else if (Document$WebAPI.isInstanceOf(t)) {
+    return {
+      TAG: "Document",
+      _0: t
+    };
+  } else {
+    return "Null";
+  }
+}
+
+export {
+  decode,
+}
+/* Element-WebAPI Not a pure module */
diff --git a/src/IntersectionObserverAPI/IntersectionObserverRoot.res b/src/IntersectionObserverAPI/IntersectionObserverRoot.res
new file mode 100644
index 0000000..7bb8c75
--- /dev/null
+++ b/src/IntersectionObserverAPI/IntersectionObserverRoot.res
@@ -0,0 +1,22 @@
+open DOMAPI
+open IntersectionObserverAPI
+
+external fromDocument: document => root = "%identity"
+external fromElement: element => root = "%identity"
+external fromNull: root = "null"
+
+type decoded =
+  | Element(element)
+  | Document(document)
+  | Null
+
+let decode = (t: root): decoded => {
+  open Prelude
+  if Element.isInstanceOf(t) {
+    Element(t->unsafeConversation)
+  } else if Document.isInstanceOf(t) {
+    Document(t->unsafeConversation)
+  } else {
+    Null
+  }
+}
diff --git a/tests/IntersectionObserverAPI/IntersectionObserver__test.js b/tests/IntersectionObserverAPI/IntersectionObserver__test.js
new file mode 100644
index 0000000..113ecec
--- /dev/null
+++ b/tests/IntersectionObserverAPI/IntersectionObserver__test.js
@@ -0,0 +1,57 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Primitive_option from "rescript/lib/es6/Primitive_option.js";
+import * as IntersectionObserverRoot$WebAPI from "../../src/IntersectionObserverAPI/IntersectionObserverRoot.js";
+
+let observer = new IntersectionObserver((entry, observer) => {
+  console.log(entry, observer);
+});
+
+let root = document.querySelector("#root");
+
+let observer2 = new IntersectionObserver((entry, observer) => {
+  console.log(entry, observer);
+}, {
+  root: Primitive_option.some(root),
+  rootMargin: "10px",
+  threshold: [0.1]
+});
+
+let match = IntersectionObserverRoot$WebAPI.decode(observer2.root);
+
+if (typeof match !== "object") {
+  console.log("Null");
+} else if (match.TAG === "Element") {
+  console.log("Element");
+} else {
+  console.log("Document");
+}
+
+let rootMargin2 = observer2.rootMargin;
+
+let targetElement = document.querySelector("#targetElement");
+
+if (targetElement !== null) {
+  observer2.observe(targetElement);
+  observer2.unobserve(targetElement);
+} else {
+  console.log("Target element not found.");
+}
+
+let entries2 = observer2.takeRecords();
+
+console.log(entries2.length);
+
+observer2.disconnect();
+
+let targetElement$1 = targetElement === null ? undefined : Primitive_option.some(targetElement);
+
+export {
+  observer,
+  root,
+  observer2,
+  rootMargin2,
+  targetElement$1 as targetElement,
+  entries2,
+}
+/* observer Not a pure module */
diff --git a/tests/IntersectionObserverAPI/IntersectionObserver__test.res b/tests/IntersectionObserverAPI/IntersectionObserver__test.res
new file mode 100644
index 0000000..eeba8c8
--- /dev/null
+++ b/tests/IntersectionObserverAPI/IntersectionObserver__test.res
@@ -0,0 +1,34 @@
+let observer = IntersectionObserver.make(~callback=(entry, observer) => {
+  Console.log2(entry, observer)
+})
+
+let root = Global.document->Document.querySelector("#root")->Null.getUnsafe
+
+let observer2 = IntersectionObserver.make(~callback=(entry, observer) => {
+  Console.log2(entry, observer)
+}, ~options={
+  root: root->IntersectionObserverRoot.fromElement,
+  rootMargin: "10px",
+  threshold: [0.1],
+})
+
+switch observer2.root->IntersectionObserverRoot.decode {
+| Element(_) => Console.log("Element")
+| Document(_) => Console.log("Document")
+| Null => Console.log("Null")
+}
+let rootMargin2 = observer2.rootMargin
+
+let targetElement = Global.document->Document.querySelector("#targetElement")->Null.toOption
+switch targetElement {
+| Some(e) => {
+    observer2->IntersectionObserver.observe(e)
+    observer2->IntersectionObserver.unobserve(e)
+  }
+| _ => Console.log("Target element not found.")
+}
+
+let entries2 = observer2->IntersectionObserver.takeRecords
+Console.log(entries2->Array.length)
+
+observer2->IntersectionObserver.disconnect