我如何检查给定的用户名和密码是否是用户输入的内容并提示成功或失败？HTML 和 JS

Question

如标题所述，我如何检查给定的用户名和密码是否是用户输入的内容并提示成功或失败？警报不再弹出。我将 js 脚本嵌入到 html 文件中。

这是脚本：

        function login() {

            var username = ["user1", "user2", "user3"];

            var password = ["1", "2", "3"];

            var idInput = document.getElementById("id");

            var pwInput = document.getElementById("pw");

            if (username[0] == idInput) {

                if (password[0] == pwInput) {

                    alert("login success!");

                } else if (username[1] == idInput) {

                    if (password[1] == pwInput) {

                        alert("login success!");    

                    } else if (username[2] == idInput) {

                        if (password[2] == pwInput) {

                            alert("login success!");                            

                        } else { 

                            alert("please try again"); 

                        }

                    } else { 

                        alert ("please try again");

                    } 

                } else { 

                    alert ("please try again");

                }   

            }

        }

这是通过 html 和按钮输入的正文：

<table>

    <tr>

        <td>Login Id:</td>

        <th>        

        <INPUT type="text" Size="40" Maxlength="35" id="id" placeholder="Your Username Here">

        </th>

    </tr>

    <tr>

        <td>Password:</td>

        <th>

        <INPUT type="text" Size="40" Maxlength="40" id="pw" placeholder="Your Password Here">

        </th>

    </tr>

</table>

<button onclick="login()">Login</button>

Answer 1

您需要更改以下几行。您正在使用对象，但不是输入的值。您需要引用对象的 value 属性才能获得实际输入。var&nbsp;idInput&nbsp;=&nbsp;document.getElementById("id").value; var&nbsp;pwInput&nbsp;=&nbsp;document.getElementById("pw").value;

Answer 2

写这个 if 的更好方法是if(idInput == username[0] && pwInput == password[0]){}else if(idInput == username[1] && pwInput == password[1]{}else if(idInput == username[2] && pwInput == password[2]{}else {&nbsp; &nbsp; alert(“User or password wrong.”);}如果您有可变数量的用户，则可以执行循环：function loginCheck(username, password, idInput, pwInput){for(i = 0; i <&nbsp; username.length; i++){&nbsp; &nbsp; if(username[i] == idInput && password[i] == pwInput)&nbsp; &nbsp; &nbsp; &nbsp; return 1;}return 0;}现在是一个安全问题：永远不要在客户端进行此检查。不良用户可以尝试阅读您的代码并获得访问权限。更好的方法是在将加密数据发送到 Web 服务器检查（例如 PHP）之前，使用哈希（推荐 SHA 256）对 idInput 和 pwInput 进行加密。因此，您可以防止不良用户访问，并且您的用户可以防止密码泄露。

Answer 3

首先，您试图评估元素而不是它们的价值。此外，您还有很多不必要的条件。我们还想重组我们存储登录凭据的方式，使其更直观。function login() {&nbsp; &nbsp; // Instead of storing usernames and passwords in separate arrays,&nbsp; &nbsp; // we instead will store them as an array of objects with username&nbsp; &nbsp; // and password properties&nbsp; &nbsp; var logins = [&nbsp; &nbsp; &nbsp; { username: 'user1', password: '1' },&nbsp; &nbsp; &nbsp; { username: 'user2', password: '2' },&nbsp; &nbsp; &nbsp; { username: 'user3', password: '3' }&nbsp; &nbsp; ];&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; // Get the values of our inputs&nbsp; &nbsp; var idInput = document.getElementById("id").value;&nbsp; &nbsp; var pwInput = document.getElementById("pw").value;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; // The find method on array returns the first occurrence in the&nbsp; &nbsp; // array if the condition evaluates to true. In this case, we&nbsp; &nbsp; // need to make sure the username and password match what was&nbsp;&nbsp; &nbsp; // entered. The !== undefined determines whether or not find&nbsp; &nbsp; // returned a match that met the search criteria.&nbsp; &nbsp; const success = logins.find(login => login.username == idInput && login.password == pwInput) !== undefined;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; // If it found a match, then we alert the appropriate response.&nbsp; &nbsp; if(success) {&nbsp; &nbsp; &nbsp; alert('Successful login!');&nbsp; &nbsp; } else {&nbsp; &nbsp; &nbsp; alert('Failed login!');&nbsp; &nbsp; }}<table>&nbsp; &nbsp; <tr>&nbsp; &nbsp; &nbsp; &nbsp; <td>Login Id:</td>&nbsp; &nbsp; &nbsp; &nbsp; <th>&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; <INPUT type="text" Size="40" Maxlength="35" id="id" placeholder="Your Username Here">&nbsp; &nbsp; &nbsp; &nbsp; </th>&nbsp; &nbsp; </tr>&nbsp; &nbsp; <tr>&nbsp; &nbsp; &nbsp; &nbsp; <td>Password:</td>&nbsp; &nbsp; &nbsp; &nbsp; <th>&nbsp; &nbsp; &nbsp; &nbsp; <INPUT type="text" Size="40" Maxlength="40" id="pw" placeholder="Your Password Here">&nbsp; &nbsp; &nbsp; &nbsp; </th>&nbsp; &nbsp; </tr></table><button onclick="login()">Login</button>