Filter out undefined query parameters and headers

src/merge.ts

@@ -2,6 +2,7 @@ import { EndpointDefaults, RequestParameters, Route } from "@octokit/types";
 
 import { lowercaseKeys } from "./util/lowercase-keys";
 import { mergeDeep } from "./util/merge-deep";
+import { removeUndefinedProperties } from "./util/remove-undefined-properties";
 
 export function merge(
   defaults: EndpointDefaults | null,
@@ -18,6 +19,10 @@ export function merge(
   // lowercase header names before merging with defaults to avoid duplicates
   options.headers = lowercaseKeys(options.headers);
 
+  // remove properties with undefined values before merging
+  removeUndefinedProperties(options);
+  removeUndefinedProperties(options.headers);
+
   const mergedOptions = mergeDeep(defaults || {}, options) as EndpointDefaults;
 
   // mediaType.previews arrays are merged, instead of overwritten

src/util/remove-undefined-properties.ts

@@ -0,0 +1,8 @@
+export function removeUndefinedProperties(obj: any): any {
+  for (const key in obj) {
+    if (obj[key] === undefined) {
+      delete obj[key];
+    }
+  }
+  return obj;
+}

test/endpoint.test.ts

@@ -410,4 +410,33 @@ describe("endpoint()", () => {
       },
     });
   });
+
+  it("Undefined query parameter", () => {
+    const options = endpoint({
+      method: "GET",
+      url: "/notifications",
+      before: undefined,
+    });
+
+    expect(options).toEqual({
+      method: "GET",
+      url: "https://api.github.com/notifications",
+      headers: {
+        accept: "application/vnd.github.v3+json",
+        "user-agent": userAgent,
+      },
+    });
+  });
+
+  it("Undefined header value", () => {
+    const options = endpoint({
+      method: "GET",
+      url: "/notifications",
+      headers: {
+        "if-modified-since": undefined,
+      },
+    });
+
+    expect(options).not.toHaveProperty("headers.if-modified-since");
+  });
 });