feat: extract DOM node check and retrieval to separate function (#539)

* feat: extract DOM node check and retrieval to separate function

* chore: rename

* typo

* chore: rename

src/Dom/findDOMNode.ts

@@ -7,22 +7,34 @@ export function isDOM(node: any): node is HTMLElement | SVGElement {
   return node instanceof HTMLElement || node instanceof SVGElement;
 }
 
+/**
+ * Retrieves a DOM node via a ref, and does not invoke `findDOMNode`.
+ */
+export function getDOM(node: any): node is HTMLElement | SVGElement {
+  if (node && typeof node === 'object' && isDOM(node.nativeElement)) {
+    return node.nativeElement;
+  }
+
+  if (isDOM(node)) {
+    return node as any;
+  }
+
+  return null;
+}
+
 /**
  * Return if a node is a DOM node. Else will return by `findDOMNode`
  */
 export default function findDOMNode<T = Element | Text>(
   node: React.ReactInstance | HTMLElement | SVGElement | { nativeElement: T },
 ): T {
-  if (node && typeof node === 'object' && isDOM((node as any).nativeElement)) {
-    return ((node as any).nativeElement as unknown) as T;
-  }
-
-  if (isDOM(node)) {
-    return (node as unknown) as T;
+  const domNode = getDOM(node);
+  if (domNode) {
+    return domNode as T;
   }
 
   if (node instanceof React.Component) {
-    return (ReactDOM.findDOMNode(node) as unknown) as T;
+    return ReactDOM.findDOMNode(node) as unknown as T;
   }
 
   return null;

tests/findDOMNode.test.tsx

@@ -1,6 +1,6 @@
 import { render } from '@testing-library/react';
 import * as React from 'react';
-import findDOMNode, { isDOM } from '../src/Dom/findDOMNode';
+import findDOMNode, { getDOM, isDOM } from '../src/Dom/findDOMNode';
 import proxyObject from '../src/proxyObject';
 
 describe('findDOMNode', () => {
@@ -129,4 +129,31 @@ describe('findDOMNode', () => {
       container.querySelector('span'),
     );
   });
+
+  describe('getDOM', () => {
+    it('should return the DOM node when input is a DOM node', () => {
+      const node = document.createElement('div');
+      const result = getDOM(node);
+
+      expect(result).toBe(node);
+    });
+
+    it('should return the nativeElement when input is an object with a DOM node as nativeElement', () => {
+      const nativeElement = document.createElement('div');
+      const node = { nativeElement };
+
+      const result = getDOM(node);
+
+      expect(result).toBe(nativeElement);
+    });
+
+    it.each([null, void 0, { foo: 'bar' }, 'string'])(
+      'should return null when input is not a DOM node',
+      node => {
+        const result = getDOM(node);
+
+        expect(result).toBeNull();
+      },
+    );
+  });
 });