London | Rihanna Poursoltani | Module-Decomposition | Sprint 3 | Middleware exercises

script.js

@@ -0,0 +1,47 @@
+import express from "express"
+const app = express();
+
+app.use(express.json());
+
+function usernameExtractor(req, res, next) {
+  const username = req.get("X-Username");
+  req.username = username ? username : null;
+  next();
+}
+
+app.post("/", usernameExtractor,(req, res) => {
+  const username = req.username;
+  const subjects = req.body;
+   if (!Array.isArray(subjects)) {
+        return res.status(400).send("Error: Body must be a JSON array.");
+    }
+
+    const CheckAllStrings = subjects.every((e) => typeof e === "string");
+  if (!CheckAllStrings) {
+    return res
+      .status(400)
+      .send("Error: Array must contain only string elements.");
+  }
+
+  let response = username
+    ? `You are authenticated as ${username}.\n`
+    : `You are not authenticated.\n`;
+
+  const count = subjects.length;
+  const subjectArr = subjects.join(", ");
+  if (count === 0) {
+    response += "You have requested information about 0 subject.";
+  } else {
+    const plural = count > 1 ? "subjects" : "subject";
+    response += `You have requested information about ${count} ${plural}: ${subjectArr}.`;
+  }
+
+
+
+  res.send(response);
+});
+
+const PORT = 3000;
+app.listen(PORT, () => {
+  console.log(`Server running on http://localhost:${PORT}`);
+});