增加注册条件限制，要求数字，字母和特殊字符

app/static/js/password.js

@@ -0,0 +1,14 @@
+function containsDigitsLettersSpecialCharacters(s) {
+    let resultD = 0, resultL = 0, resultS = 0;
+
+    // Digit test
+    resultD = /\d/.test(s);
+
+    // Letter test
+    resultL = /[a-zA-Z]/.test(s);
+
+    // Special character test
+    resultS = /[!@#$%^&*(),.?":{}|<>]/.test(s);
+
+    return resultD + resultL + resultS == 3;
+}

app/templates/signup.html

@@ -24,6 +24,10 @@ You're logged in already! <a href="/logout">Logout</a>.
                 alert('密码过于简单。(密码长度至少4位)');
                 return false;
             }
+            if (!containsDigitsLettersSpecialCharacters(password)) {
+            alert('密码过于简单。(密码要包括数字，字母，特殊符号)');
+            return false;
+            }
             $.post("/signup", {'username': username, 'password': password},
                 function (response) {
                     if (response.status === '0') {