Support experimental partitioned cookies (#12)

Co-authored-by: Theodore Brown <[email protected]>

README.md

@@ -196,6 +196,21 @@ Cookies.set('name', 'value', { sameSite: 'strict' });
 Cookies.set('other', 'value', { sameSite: 'lax' });
 ```
 
+### partitioned
+
+Either `true` or `false`, indicating that the cookie should be stored using partitioned storage.
+See [Cookies Having Independent Partitioned State (CHIPS)](https://developer.mozilla.org/en-US/docs/Web/Privacy/Privacy_sandbox/Partitioned_cookies) for more details.
+
+**Default:** Cookie will not be partitioned.
+
+**Examples:**
+
+```javascript
+Cookies.set('name', 'value', { secure: true, partitioned: true });
+Cookies.get('name'); // => 'value'
+Cookies.remove('name');
+```
+
 ## Encoding
 
 This project is [RFC 6265](http://tools.ietf.org/html/rfc6265#section-4.1.1)

src/CookieAttributes.ts

@@ -1,4 +1,4 @@
-export type CookieAttributes = BaseCookieAttributes & SameSiteCookieAttributes;
+export type CookieAttributes = BaseCookieAttributes & SameSiteCookieAttributes & MaybePartitionedCookie;
 
 interface BaseCookieAttributes {
     /**
@@ -41,10 +41,26 @@ interface LaxStrictSameSiteCookieAttributes {
     sameSite?: 'strict' | 'lax';
 }
 
-/**
- * Cookies with `SameSite=None` must also specify 'Secure'
- */
+/** Cookies with `SameSite=None` must also specify 'Secure' */
 interface NoneSameSiteCookieAttributes {
     sameSite: 'none';
     secure: true;
 }
+
+type MaybePartitionedCookie = UnpartitionedCookieAttributes | PartitionedCookieAttributes;
+
+interface UnpartitionedCookieAttributes {
+    /**
+     * If enabled, indicates that the cookie should be stored using partitioned storage.
+     */
+    partitioned?: false;
+}
+
+/** Cookies with `Partitioned` must also specify 'Secure' */
+interface PartitionedCookieAttributes {
+    /**
+     * Indicates that the cookie should be stored using partitioned storage.
+     */
+    partitioned: true;
+    secure: true;
+}

src/es-cookie.ts

@@ -26,6 +26,7 @@ function stringifyAttributes(attributes: CookieAttributes): string {
         + stringifyAttribute('Domain', attributes.domain)
         + stringifyAttribute('Path', attributes.path)
         + stringifyAttribute('Secure', attributes.secure)
+        + stringifyAttribute('Partitioned', attributes.partitioned)
         + stringifyAttribute('SameSite', attributes.sameSite);
 }
 

test/tests.ts

@@ -148,6 +148,16 @@ describe('encode', function () {
         assert.strictEqual(actual, 'c=v; Path=/');
     });
 
+    it('should support true partitioned option', function () {
+        let actual = Cookies.encode('c', 'v', { secure: true, partitioned: true });
+        assert.strictEqual(actual, 'c=v; Secure; Partitioned');
+    });
+
+    it('should support false partitioned option', function () {
+        let actual = Cookies.encode('c', 'v', { partitioned: false });
+        assert.strictEqual(actual, 'c=v');
+    });
+
     it('should support sameSite option', function() {
         let strict = Cookies.encode('c', 'v', { sameSite: 'strict' });
         assert.strictEqual(strict, 'c=v; SameSite=strict');