feat: adds JWT example

examples/creating-and-verifying-jwt.ts

@@ -0,0 +1,58 @@
+/**
+ * @title Creating and verifying JWT
+ * @difficulty intermediate
+ * @tags cli, deploy
+ * @run <url>
+ * @resource {https://deno.land/x/jose} Doc: jose library for Deno
+ * @group Authentication
+ *
+ * This example demonstrates how to create and verify a JSON Web Token (JWT)
+ * using the `jose` library in Deno. JWTs are often used for secure
+ * communication between a client and server, enabling stateless
+ * authentication. This script includes functions to generate and verify
+ * tokens using the HS256 algorithm.
+ */
+
+// Import necessary functions and types from the `jose` library.
+import {
+  JWTPayload,
+  jwtVerify,
+  SignJWT,
+} from "https://deno.land/x/[email protected]/index.ts";
+
+// Define a secret key used for signing and verifying JWTs. Ensure that this secret is kept secure in a real-world application.
+const secret = new TextEncoder().encode("secret-that-no-one-knows");
+
+// Creates a JSON Web Token (JWT) with a specified payload and signed using the HS256 algorithm and has a 1-hour expiration time.
+async function createJWT(payload: JWTPayload): Promise<string> {
+  const jwt = await new SignJWT(payload)
+    .setProtectedHeader({ alg: "HS256" })
+    .setIssuedAt()
+    .setExpirationTime("1h")
+    .sign(secret);
+
+  return jwt;
+}
+
+// Verifies a given JSON Web Token (JWT) using the secret key. If valid, returns the payload data contained in the JWT else logs the error and returns null.
+async function verifyJWT(token: string): Promise<JWTPayload | null> {
+  try {
+    // Verify the JWT using the secret key and extract the payload.
+    const { payload } = await jwtVerify(token, secret);
+    console.log("JWT is valid:", payload);
+    return payload;
+  } catch (error) {
+    console.error("Invalid JWT:", error);
+    return null;
+  }
+}
+
+(async () => {
+  // Creating a JWT with user-specific information.
+  const token = await createJWT({ userId: 123, username: "john_doe" });
+  console.log("Created JWT:", token);
+
+  // Verifying the generated JWT to ensure it has not been tampered with.
+  const verifiedPayload = await verifyJWT(token);
+  console.log("Verified Payload:", verifiedPayload);
+})();