apiのサンプル

package.json

@@ -15,6 +15,7 @@
     "react-dom": "^16.8.6"
   },
   "devDependencies": {
+    "@types/express": "^4.17.0",
     "@types/node": "^12.6.1",
     "typescript": "^3.5.3"
   },

pages/api/headers.ts

@@ -0,0 +1,3 @@
+import { Handler } from "express";
+export const handler: Handler = (req, res) => res.json(req.headers);
+export default handler;

yarn.lock

@@ -923,6 +923,43 @@
   resolved "https://registry.yarnpkg.com/@next/mdx/-/mdx-9.0.0.tgz#e7df99fe520935f2176b7abf6cf801e7d2a792bb"
   integrity sha512-0lgBqHFAn2NzV3c8OpEhvu1H/hmck/D2bLrF63lLjhe67oRoBGNBNtfYKDnmmff7aC0PnxFeEwcmAM9RgXHTCA==
 
+"@types/body-parser@*":
+  version "1.17.0"
+  resolved "https://registry.yarnpkg.com/@types/body-parser/-/body-parser-1.17.0.tgz#9f5c9d9bd04bb54be32d5eb9fc0d8c974e6cf58c"
+  integrity sha512-a2+YeUjPkztKJu5aIF2yArYFQQp8d51wZ7DavSHjFuY1mqVgidGyzEQ41JIVNy82fXj8yPgy2vJmfIywgESW6w==
+  dependencies:
+    "@types/connect" "*"
+    "@types/node" "*"
+
+"@types/connect@*":
+  version "3.4.32"
+  resolved "https://registry.yarnpkg.com/@types/connect/-/connect-3.4.32.tgz#aa0e9616b9435ccad02bc52b5b454ffc2c70ba28"
+  integrity sha512-4r8qa0quOvh7lGD0pre62CAb1oni1OO6ecJLGCezTmhQ8Fz50Arx9RUszryR8KlgK6avuSXvviL6yWyViQABOg==
+  dependencies:
+    "@types/node" "*"
+
+"@types/express-serve-static-core@*":
+  version "4.16.7"
+  resolved "https://registry.yarnpkg.com/@types/express-serve-static-core/-/express-serve-static-core-4.16.7.tgz#50ba6f8a691c08a3dd9fa7fba25ef3133d298049"
+  integrity sha512-847KvL8Q1y3TtFLRTXcVakErLJQgdpFSaq+k043xefz9raEf0C7HalpSY7OW5PyjCnY8P7bPW5t/Co9qqp+USg==
+  dependencies:
+    "@types/node" "*"
+    "@types/range-parser" "*"
+
+"@types/express@^4.17.0":
+  version "4.17.0"
+  resolved "https://registry.yarnpkg.com/@types/express/-/express-4.17.0.tgz#49eaedb209582a86f12ed9b725160f12d04ef287"
+  integrity sha512-CjaMu57cjgjuZbh9DpkloeGxV45CnMGlVd+XpG7Gm9QgVrd7KFq+X4HY0vM+2v0bczS48Wg7bvnMY5TN+Xmcfw==
+  dependencies:
+    "@types/body-parser" "*"
+    "@types/express-serve-static-core" "*"
+    "@types/serve-static" "*"
+
+"@types/mime@*":
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/@types/mime/-/mime-2.0.1.tgz#dc488842312a7f075149312905b5e3c0b054c79d"
+  integrity sha512-FwI9gX75FgVBJ7ywgnq/P7tw+/o1GUbtP0KzbtusLigAOgIgNISRK0ZPl4qertvXSIE8YbsVJueQ90cDt9YYyw==
+
 "@types/node@*", "@types/node@^12.6.1":
   version "12.6.1"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-12.6.1.tgz#d5544f6de0aae03eefbb63d5120f6c8be0691946"
@@ -933,6 +970,11 @@
   resolved "https://registry.yarnpkg.com/@types/prop-types/-/prop-types-15.7.1.tgz#f1a11e7babb0c3cad68100be381d1e064c68f1f6"
   integrity sha512-CFzn9idOEpHrgdw8JsoTkaDDyRWk1jrzIV8djzcgpq0y9tG4B4lFT+Nxh52DVpDXV+n4+NPNv7M1Dj5uMp6XFg==
 
+"@types/range-parser@*":
+  version "1.2.3"
+  resolved "https://registry.yarnpkg.com/@types/range-parser/-/range-parser-1.2.3.tgz#7ee330ba7caafb98090bece86a5ee44115904c2c"
+  integrity sha512-ewFXqrQHlFsgc09MK5jP5iR7vumV/BYayNC6PgJO2LPe8vrnNFyjQjSppfEngITi0qvfKtzFvgKymGheFM9UOA==
+
 "@types/react-transition-group@^2.0.16":
   version "2.9.2"
   resolved "https://registry.yarnpkg.com/@types/react-transition-group/-/react-transition-group-2.9.2.tgz#c48cf2a11977c8b4ff539a1c91d259eaa627028d"
@@ -948,6 +990,14 @@
     "@types/prop-types" "*"
     csstype "^2.2.0"
 
+"@types/serve-static@*":
+  version "1.13.2"
+  resolved "https://registry.yarnpkg.com/@types/serve-static/-/serve-static-1.13.2.tgz#f5ac4d7a6420a99a6a45af4719f4dcd8cd907a48"
+  integrity sha512-/BZ4QRLpH/bNYgZgwhKEh+5AsboDBcUdlBYgzoLX0fpj3Y2gp6EApyOlM3bK53wQS/OE1SrdSYBAbux2D1528Q==
+  dependencies:
+    "@types/express-serve-static-core" "*"
+    "@types/mime" "*"
+
 "@types/unist@*", "@types/unist@^2.0.0":
   version "2.0.3"
   resolved "https://registry.yarnpkg.com/@types/unist/-/unist-2.0.3.tgz#9c088679876f374eb5983f150d4787aa6fb32d7e"