Add React interopt guide (#886)

* Add React interopt guide

* Rename to interop

* Use CodeTab

* Rename interop to import-export-reactjs

Author: nojaf

data/sidebar_react_latest.json

@@ -14,7 +14,8 @@
     "context",
     "styling",
     "router",
-    "lazy-components"
+    "lazy-components",
+    "import-export-reactjs"
   ],
   "Hooks & State Management": [
     "hooks-overview",

pages/docs/manual/latest/import-from-export-to-js.mdx

@@ -8,6 +8,8 @@ canonical: "/docs/manual/latest/import-from-export-to-js"
 
 You've seen how ReScript's idiomatic [Import & Export](import-export.md) works. This section describes how we work with importing stuff from JavaScript and exporting stuff for JavaScript consumption.
 
+If you're looking for react-specific interop guidance, check out the [React JS Interop guide](../../react/latest/import-export-reactjs.mdx).
+
 **Note**: due to JS ecosystem's module compatibility issues, our advice of keeping your ReScript file's compiled JS output open in a tab applies here **more than ever**, as you don't want to subtly output the wrong JS module import/export code, on top of having to deal with Babel/Webpack/Jest/Node's CommonJS \<-> JavaScript module compatibility shims.
 
 In short: **make sure your bindings below output what you'd have manually written in JS**.

pages/docs/react/latest/import-export-reactjs.mdx

@@ -0,0 +1,189 @@
+---
+title: Import / Export ReactJS
+description: "Reusing existing React components"
+canonical: "/docs/react/latest/import-export-reactjs"
+---
+
+# Import / Export ReactJS
+
+Reusing existing React components in ReScript is straightforward. 
+This guide will walk you through the steps required to import and use React components within ReScript,
+including defining component props and handling various import scenarios.
+
+## Basic Example
+
+To reuse a React component in ReScript, create a new module, specify the component's location, and define its props.
+
+<CodeTab labels={["ReScript", "JS Output"]}>
+
+```res
+module Confetti = {
+  @module("react-confetti") @react.component
+  external make: (~width: int, ~height: int) => React.element = "default"
+}
+
+// Assuming we are in App.res
+@react.component
+let make = () => {
+  <Confetti width={300} height={300} />
+}
+```
+
+```js
+import ReactConfetti from "react-confetti";
+import * as JsxRuntime from "react/jsx-runtime";
+
+var Confetti = {};
+
+function Playground(props) {
+  return JsxRuntime.jsx(ReactConfetti, {
+              width: 300,
+              height: 300
+            });
+}
+```
+
+</CodeTab>
+
+## Importing from Relative Paths
+
+You can import components from relative file paths using the `@module` attribute.  
+Use "default" to indicate the default export, or specify a named export if needed.
+
+### Named Export Example 
+
+<CodeTab labels={["ReScript"]}>
+
+```res
+// Equivalent of import { Foo } from "bar"
+module Foo = {
+  @module("bar") @react.component
+  external make: unit => React.element = "Foo"
+}
+```
+
+</CodeTab>
+
+## Defining Props Types
+
+You can define a separate type for your component's props within the module.
+
+### Props Type Example
+
+<CodeTab labels={["ReScript", "JS Output"]}>
+
+```res
+module Confetti = {
+  type confettiProps = {
+    width: int,
+    height: int,
+  }
+
+  @module("react-confetti") @react.component(: confettiProps)
+  external make: confettiProps => React.element = "default"
+}
+
+@react.component
+let make = () => {
+  <Confetti width={300} height={300} />
+}
+```
+
+```js
+import ReactConfetti from "react-confetti";
+import * as JsxRuntime from "react/jsx-runtime";
+
+var Confetti = {};
+
+function Playground(props) {
+  return JsxRuntime.jsx(ReactConfetti, {
+              width: 300,
+              height: 300
+            });
+}
+```
+
+</CodeTab>
+
+## Optional Props
+
+To define optional props, use the `?` symbol.
+
+<CodeTab labels={["ReScript", "JS Output"]}>
+
+```res
+module Confetti = {
+  type confettiProps = {
+    width: int,
+    height: int,
+    initialVelocityX?: int,
+    initialVelocityY?: int,
+  }
+
+  @module("react-confetti") @react.component(: confettiProps)
+  external make: confettiProps => React.element = "default"
+}
+
+@react.component
+let make = () => {
+  <Confetti width={300} height={300} />
+}
+```
+
+```js
+import ReactConfetti from "react-confetti";
+import * as JsxRuntime from "react/jsx-runtime";
+
+var Confetti = {};
+
+function Playground(props) {
+  return JsxRuntime.jsx(ReactConfetti, {
+              width: 300,
+              height: 300
+            });
+}
+```
+
+</CodeTab>
+
+## Extending Built-in DOM Nodes
+
+To accept existing DOM props for a component, extend the `JsxDOM.domProps` type.
+
+<CodeTab labels={["ReScript", "JS Output"]}>
+
+```res
+module Foo = {
+  type fooProps = {
+    ...JsxDOM.domProps,
+    customProp: string,
+  }
+
+  @module("foo") @react.component(: fooProps)
+  external make: fooProps => React.element = "default"
+}
+
+@react.component
+let make = () => {
+  <Foo width={"300px"} height={"300px"} customProp="bar" />
+}
+```
+
+```js
+import Foo from "foo";
+import * as JsxRuntime from "react/jsx-runtime";
+
+var Foo$1 = {};
+
+function Playground(props) {
+  return JsxRuntime.jsx(Foo, {
+              height: "300px",
+              width: "300px",
+              customProp: "bar"
+            });
+}
+```
+
+</CodeTab>
+
+In this example `width` and `height` can be set because `JsxDOM.domProps` was spread into `fooProps`.