register functionality added

backend/register.php

+<?php
+include_once("database.php");
+$postData = file_get_contents("php://input");
+
+if (isset($postData) && !empty($postData)) {
+    $request = json_decode($postData);
+    $name = trim($request->name);
+    $pwd = password_hash(mysqli_real_escape_string($mysqli, trim($request->pwd)), PASSWORD_DEFAULT);
+    $email = mysqli_real_escape_string($mysqli, trim($request->email));
+    $username = mysqli_real_escape_string($mysqli, trim($request->username));
+    $sql = "INSERT INTO users(name,password,email,username) VALUES ('$name','$pwd','$email','$username')";
+
+    if ($mysqli->query($sql) === TRUE) {
+        $authData = [
+            'name' => $name,
+            'pwd' => $pwd,
+            'email' => $email,
+            'id' => mysqli_insert_id($mysqli),
+            'username' => $username
+        ];
+        echo json_encode($authData);
+    } else {
+        echo "mysqli_error($mysqli)";
+    }
+}