implemented additional route for checking usernames

controllers/auth.js

@@ -102,8 +102,31 @@ function logout() {
   });
 }
 
+function checkUser(username) {
+  if (!username) {
+    return Promise.reject({
+      success: false,
+      message: 'Username is not provided',
+    });
+  }
+  return User.findOne({ username: username.toLowerCase() })
+    .exec()
+    .then((user) => {
+      if (user) {
+        return Promise.reject({
+          success: false,
+          message: 'Username is already taken',
+        });
+      }
+      return Promise.resolve({
+        success: true,
+      });
+    });
+}
+
 module.exports = {
   signUp,
   login,
   logout,
+  checkUser,
 };

routes/auth.js

@@ -1,3 +1,4 @@
+const url = require('url');
 const { Router } = require('express');
 const authConroller = require('../controllers/auth');
 
@@ -67,4 +68,22 @@ authRouter.get('/logout', (req, res, next) => {
     });
 });
 
+authRouter.get('/check-user', (req, res, next) => {
+  const { query } = url.parse(req.url, true).query;
+  authConroller
+    .checkUser(query)
+    .then((result) => {
+      res.json({
+        success: result.success,
+      });
+    })
+    .catch((error) => {
+      res.json({
+        success: false,
+        message: error.message,
+      });
+      next(error);
+    });
+});
+
 module.exports = authRouter;