Don't write a response body for null body status codes in sendStatus

README.md

@@ -486,10 +486,16 @@ The `sendStatus` method sets the status code and returns its string representati
 
 ```javascript
 res.sendStatus(200); // equivalent to res.status(200).send('OK')
-res.sendStatus(304); // equivalent to res.status(304).send('Not Modified')
 res.sendStatus(403); // equivalent to res.status(403).send('Forbidden')
 ```
 
+Status codes that [must not carry content](https://datatracker.ietf.org/doc/html/rfc9110#name-overview-of-status-codes) per RFC 9110 — `1xx`, `204`, `205`, and `304` — are sent with an empty body instead:
+
+```javascript
+res.sendStatus(204); // equivalent to res.status(204).send('')
+res.sendStatus(304); // equivalent to res.status(304).send('')
+```
+
 **NOTE:** If an unsupported status code is provided, it will return 'Unknown' as the body.
 
 ### header(key, value [,append])

__tests__/responses.unit.js

@@ -73,6 +73,10 @@ api.get('/testSendStatus', function(req,res) {
   res.sendStatus(200)
 })
 
+api.get('/testSendStatus204', function(req,res) {
+  res.sendStatus(204)
+})
+
 api.get('/testSendStatus403', function(req,res) {
   res.sendStatus(403)
 })
@@ -180,6 +184,12 @@ describe('Response Tests:', function() {
     expect(result).toEqual({ multiValueHeaders: { 'content-type': ['application/json'] }, statusCode: 200, body: 'OK', isBase64Encoded: false })
   }) // end it
 
+  it('sendStatus 204', async function() {
+    let _event = Object.assign({},event,{ path: '/testSendStatus204'})
+    let result = await new Promise(r => api.run(_event,{},(e,res) => { r(res) }))
+    expect(result).toEqual({ multiValueHeaders: { 'content-type': ['application/json'] }, statusCode: 204, body: '', isBase64Encoded: false })
+  }) // end it
+
   it('sendStatus 403', async function() {
     let _event = Object.assign({},event,{ path: '/testSendStatus403'})
     let result = await new Promise(r => api.run(_event,{},(e,res) => { r(res) }))

__tests__/utils.unit.js

@@ -232,6 +232,28 @@ describe("Utility Function Tests:", function () {
     }); // end it
   }); // end encodeBody tests
 
+  describe("statusBodyLookup:", function () {
+    test.each([
+      [100, ""],
+      [101, ""],
+      [200, "OK"],
+      ["200", "OK"],
+      [204, ""],
+      ["204", ""],
+      [205, ""],
+      ["205", ""],
+      [304, ""],
+      ["304", ""],
+      [404, "Not Found"],
+      [502, "Bad Gateway"],
+      [999, "Unknown"],
+      ["not a number", "Unknown"]
+    ])("%s", (status, expected) => {
+      expect(utils.statusBodyLookup(status)).toBe(expected);
+    }); // end it
+  }); // end statusBodyLookup tests
+
+
   describe("extractRoutes:", function () {
     it("Sample routes", function () {
       // Create an api instance

src/lib/response.js

@@ -415,7 +415,7 @@ class RESPONSE {
 
   // Convenience method for sending status codes
   sendStatus(status) {
-    this.status(status).send(UTILS.statusLookup(status));
+    this.status(status).send(UTILS.statusBodyLookup(status));
   }
 
   // Convenience method for setting CORS headers

src/lib/utils.js

@@ -114,6 +114,18 @@ export const statusLookup = (status) => {
   return status in statusCodes ? statusCodes[status] : 'Unknown';
 };
 
+export const statusBodyLookup = (status) => {
+  const code = typeof status === 'string' ? Number(status) : status;
+
+  // The following status codes must not have a response body
+  // according to rfc 9110
+  if ((100 <= code && code < 200) || [204, 205, 304].includes(code)) {
+    return '';
+  }
+
+  return statusLookup(code);
+};
+
 // Parses routes into readable array
 const extractRoutes = (routes, table = []) => {
   // Loop through all routes