Support Node.js http.ClientRequestArgs["headers"] array (#1510)

Author: timostamm

packages/connect-node/src/node-universal-header.spec.ts

@@ -144,4 +144,26 @@ describe("webHeaderToNodeHeaders()", () => {
       d: ["d1", "d2"],
     });
   });
+  it("should accept default node headers array", () => {
+    // biome-ignore format: headers array is contiguous
+    const nodeDefaults: string[] = [
+      "a", "a",
+      "b", "b1",
+      "b", "b2",
+      "c", "123",
+    ];
+    const webHeaders: HeadersInit = [
+      ["b", "web"],
+      ["c", "456"],
+      ["d", "d1"],
+      ["d", "d2"],
+    ];
+    const h = webHeaderToNodeHeaders(webHeaders, nodeDefaults);
+    expect(h).toEqual({
+      a: "a",
+      b: ["b1", "b2", "web"],
+      c: ["123", "456"],
+      d: ["d1", "d2"],
+    });
+  });
 });

packages/connect-node/src/node-universal-header.ts

@@ -54,30 +54,48 @@ export function nodeHeaderToWebHeader(
 /**
  * Convert a fetch API Headers object to a Node.js headers object.
  *
- * Optionally accepts default Node.js headers. If provided, fetch API headers
- * are appended to the defaults. The original defaults headers are not modified.
+ * Optionally accepts default Node.js headers as a dict or an array.
+ * If provided, fetch API headers are appended to the defaults.
+ * The original defaults headers are not modified.
  */
 export function webHeaderToNodeHeaders(
   headersInit: HeadersInit,
-  defaultNodeHeaders?: http.OutgoingHttpHeaders,
+  defaultNodeHeaders?: http.OutgoingHttpHeaders | readonly string[],
 ): http.OutgoingHttpHeaders;
 export function webHeaderToNodeHeaders(
   headersInit: HeadersInit | undefined,
 ): http.OutgoingHttpHeaders | undefined;
 export function webHeaderToNodeHeaders(
   headersInit: HeadersInit | undefined,
-  defaultNodeHeaders?: http.OutgoingHttpHeaders,
+  defaultNodeHeaders?: http.OutgoingHttpHeaders | readonly string[],
 ): http.OutgoingHttpHeaders | undefined {
   if (headersInit === undefined && defaultNodeHeaders === undefined) {
     return undefined;
   }
   const o = Object.create(null) as http.OutgoingHttpHeaders;
   if (defaultNodeHeaders !== undefined) {
-    for (const [key, value] of Object.entries(defaultNodeHeaders)) {
-      if (Array.isArray(value)) {
-        o[key] = value.concat();
-      } else if (value !== undefined) {
-        o[key] = value;
+    if (Array.isArray(defaultNodeHeaders)) {
+      // headers may be an Array where the keys and values are in the same list.
+      // It is _not_ a list of tuples. So, the even-numbered offsets are key values,
+      // and the odd-numbered offsets are the associated values.
+      for (let i = 0; i + 1 < defaultNodeHeaders.length; i += 2) {
+        const key = defaultNodeHeaders[i];
+        const value = defaultNodeHeaders[i + 1];
+        if (Array.isArray(o[key])) {
+          o[key].push(value);
+        } else if (typeof o[key] == "string") {
+          o[key] = [o[key], value];
+        } else {
+          o[key] = value;
+        }
+      }
+    } else {
+      for (const [key, value] of Object.entries(defaultNodeHeaders)) {
+        if (Array.isArray(value)) {
+          o[key] = value.concat();
+        } else if (value !== undefined) {
+          o[key] = value;
+        }
       }
     }
   }