Add isSameOrigin

snippets/isSameOrigin.md

@@ -0,0 +1,21 @@
+---
+title: isSameOrigin
+tags: object,beginner
+---
+
+Checks if two URLs are on the same origin.
+
+- Use `URL.protocol` and `URL.host` to check if both URLs have the same protocol and host.
+
+```js
+const isSameOrigin = (origin, destination) =>
+  origin.protocol === destination.protocol && origin.host === destination.host;
+```
+
+```js
+const origin = new URL('https://www.30secondsofcode.org/about');
+const destination = new URL('https://www.30secondsofcode.org/contact');
+isSameOrigin(origin, destination); // true
+const other = new URL('https://developer.mozilla.org);
+isSameOrigin(origin, other); // false
+```