Docs update - JWKS example (#51)

* JWKS example updated in docs
* fast-jwt integration test updated
Co-authored-by: Sameer Srivastava <sameer.srivastava@nearform.com>

README.md

@@ -113,29 +113,26 @@ fastify.listen(3000)
 The following example shows how to use JWKS in fast-jwt via get-jwks.
 
 ```js
-const { createDecoder, createVerifier } = require('fast-jwt')
+const { createVerifier } = require('fast-jwt')
 const buildGetJwks = require('get-jwks')
 
-// JWT signed with JWKS
-const token = '...'
-
 // well known url of the token issuer
 // often encoded as the `iss` property of the token payload
 const domain = 'https://...'
 
-// complete is necessary to get the header
-const decode = createDecoder({ complete: true })
-
-// decode the token and extract the header
-const {
-  header: { kid, alg },
-} = decode(token)
-
-const getJwks = buildGetJwks()
-const publicKey = await getJwks.getPublicKey({ kid, domain, alg })
-
-const verifyWithPromise = createVerifier({ key: publicKey })
+const getJwks = buildGetJwks({ allowedDomains: [...]})
+
+// create a verifier function with key as a function
+const verifyWithPromise = createVerifier({
+  key: async function (token) {
+    const publicKey = await getJwks.getPublicKey({
+      kid: token.kid,
+      alg: token.alg,
+      domain,
+    })
+    return publicKey
+  },
+})
 
-// verify the token via the public key
 const payload = await verifyWithPromise(token)
 ```

test/fast-jwt-integration.spec.js

@@ -2,7 +2,7 @@
 
 const t = require('tap')
 const nock = require('nock')
-const { createDecoder, createVerifier } = require('fast-jwt')
+const { createVerifier } = require('fast-jwt')
 
 const { jwks, token } = require('./constants')
 const buildGetJwks = require('../src/get-jwks')
@@ -17,19 +17,20 @@ t.afterEach(async () => {
 })
 
 t.test('fast-jwt integration tests', async t => {
-  const myDomain = 'https://localhost/'
-  nock(myDomain).get('/.well-known/jwks.json').reply(200, jwks)
-
-  const decodeComplete = createDecoder({ complete: true })
-  const sections = decodeComplete(token)
-  const {
-    header: { kid, alg },
-  } = sections
+  const domain = 'https://localhost/'
+  nock(domain).get('/.well-known/jwks.json').reply(200, jwks)
 
   const getJwks = buildGetJwks()
-  const publicKey = await getJwks.getPublicKey({ kid, domain: myDomain, alg })
-
-  const verifyWithPromise = createVerifier({ key: publicKey })
+  const verifyWithPromise = createVerifier({
+    key: async function (token) {
+      const publicKey = await getJwks.getPublicKey({
+        kid: token.kid,
+        alg: token.alg,
+        domain,
+      })
+      return publicKey
+    },
+  })
   const payload = await verifyWithPromise(token)
 
   t.equal(payload.name, 'Jane Doe')