引入validation.js，修改Content-Type

static/public/js/login.js

@@ -127,7 +127,7 @@ form.addEventListener('submit', async function(e) {
 		const res = await fetch('/login', {
 			method: 'POST',
 			headers: {
-                'Content-Type': 'application/x-www-form-urlencoded'
+				'Content-Type': 'application/json'	// 告诉服务器内容为json
 			},
 			body: jsonBody
 		});

static/public/login.html

@@ -42,6 +42,7 @@
 				<span id="agreeTip"></span>
 			</div>
 		</form>
+		<script src="js/validation.js"></script>
 		<script src="js/login.js"></script>
 	</body>
 </html>