feat(options): add allowMultiple to options

src/cookie/parse.ts

@@ -19,9 +19,10 @@ export function parse(
     throw new TypeError("argument str must be a string");
   }
 
-  const obj = {};
+  const obj: Record<string, string> = {};
   const opt = options || {};
   const dec = opt.decode || decode;
+  const allowMultiple = opt.allowMultiple || false;
 
   let index = 0;
   while (index < str.length) {
@@ -48,16 +49,23 @@ export function parse(
       continue;
     }
 
-    // only assign once
-    if (undefined === obj[key as keyof typeof obj]) {
-      let val = str.slice(eqIdx + 1, endIdx).trim();
+    let val = str.slice(eqIdx + 1, endIdx).trim();
 
-      // quoted values
-      if (val.codePointAt(0) === 0x22) {
-        val = val.slice(1, -1);
-      }
+    // quoted values
+    if (val.codePointAt(0) === 0x22) {
+      val = val.slice(1, -1);
+    }
 
-      (obj as any)[key] = tryDecode(val, dec);
+    val = tryDecode(val, dec);
+
+    // handle multiple values for the same key
+    if (allowMultiple) {
+      obj[key] =
+        obj[key] === undefined || obj[key] === "" ? val : `${obj[key]},${val}`;
+    } else {
+      if (obj[key] === undefined) {
+        obj[key] = val;
+      }
     }
 
     index = endIdx + 1;

src/cookie/types.ts

@@ -142,4 +142,8 @@ export interface CookieParseOptions {
    * Custom function to filter parsing specific keys.
    */
   filter?(key: string): boolean;
+  /**
+   * Flag to allow to return multiple values when cookie is duplicated.
+   */
+  allowMultiple?: boolean;
 }

test/cookie-parse.test.ts

@@ -61,6 +61,27 @@ describe("cookie.parse(str)", () => {
       bar: "bar",
     });
   });
+
+  it("should return duplicated cookies values if `allowMultiple` is set", () => {
+    expect(
+      parse("foo=%1;bar=bar;foo=boo", { allowMultiple: true }),
+    ).toMatchObject({
+      foo: "%1,boo",
+      bar: "bar",
+    });
+    expect(
+      parse("foo=false;bar=bar;foo=true", { allowMultiple: true }),
+    ).toMatchObject({
+      foo: "false,true",
+      bar: "bar",
+    });
+    expect(
+      parse("foo=;bar=bar;foo=boo", { allowMultiple: true }),
+    ).toMatchObject({
+      foo: "boo",
+      bar: "bar",
+    });
+  });
 });
 
 describe("cookie.parse(str, options)", () => {