add support for easy JSON stringifying jar

CookieJar.ts

@@ -89,9 +89,15 @@ export class CookieJar {
   /**
    * @param cookies - the cookies array to initialize with
    */
-  constructor(cookies?: Array<Cookie>) {
+  constructor(cookies?: Array<Cookie> | Array<CookieOptions>) {
     if (cookies?.length) {
-      this.cookies = cookies;
+      if (typeof (cookies[0] as Cookie).isValid === "function") {
+        this.cookies = cookies as Array<Cookie>;
+      } else {
+        for (const cookie of cookies) {
+          this.cookies.push(new Cookie(cookie));
+        }
+      }
     }
   }
 
@@ -179,4 +185,8 @@ export class CookieJar {
       .join("; ");
     return cookiesToSend;
   }
+
+  toJSON() {
+    return this.cookies;
+  }
 }

cookie_jar_test.ts

@@ -174,3 +174,36 @@ Deno.test("CookieJar.getCookieString()", () => {
     "",
   );
 });
+
+Deno.test("CookieJar json serialization", () => {
+  const cookieStr1 = "test=nop; path=/sth; domain=.example.com";
+  const cookieStr2 = "foo=bar; path=/sth; domain=.example.com";
+  const cookie1 = Cookie.from(cookieStr1);
+  const cookie2 = Cookie.from(cookieStr2);
+
+  const cookieJar = new CookieJar([
+    cookie1,
+    cookie2,
+  ]);
+
+  const newCookieJar = new CookieJar(JSON.parse(JSON.stringify(cookieJar)));
+
+  // our before-serialized jar
+  assertStrictEquals(
+    cookieJar.getCookieString("example.com"),
+    "test=nop; foo=bar",
+  );
+  assertStrictEquals(
+    cookieJar.getCookieString("notexample.com"),
+    "",
+  );
+  // our new parsed cookie jar
+  assertStrictEquals(
+    newCookieJar.getCookieString("example.com"),
+    "test=nop; foo=bar",
+  );
+  assertStrictEquals(
+    newCookieJar.getCookieString("notexample.com"),
+    "",
+  );
+});