使用JavaScript编写简单的用户登录验证代码
```javascript function isUserLoggedIn(username, password) { // 假设我们有一个用户数据库，这里用一个对象模拟 const userDatabase = { "user1": "password1", "user2": "password2", "user3": "password3" }; // 检查用户名是否存在于数据库中 if (userDatabase.hasOwnProperty(username)) { // 如果存在，检查密码是否正确 if (userDatabase[username] === password) { return true; } else { return false; } } else { return false; } } // 示例用法 const username = "user1"; const password = "password1"; if (isUserLoggedIn(username, password)) { console.log("登录成功");
<!DOCTYPEhtml><html><head><metacharset="UTF-8"><metahttp-equiv="X-UA-Compatible"content="IE=edge"><metaname="viewport"content="width=device-width,initial-scale=1.0"><title>Document</title><script>varuserList=[{name:'张三',pwd:'123456'},{name:'李四',pwd:'654321'}]functionerrorpwd(){varnp=prompt('请重新输入密码');if(np===cp){alert('登陆成功');flag=1;}else{errorpwd();}}while(true){varn=prompt('请输入账号');for(vari=0;i<userList.length;i++){if(n===userList[i].name){varnum=i;varp=prompt('请输入密码');if(p===userList[num].pwd){alert('登陆成功');varflag=1;break;}else{alert('密码错误');cp=userList[num].pwd;errorpwd();break;}}}if(flag===1){break;}}</script></head><body></body></html>
