Question

我是javascript的新手。我希望当用户在注册时输入用户名并且该名称已存在于数据库中时，我将显示Name already exists的提示。你需要输入另一个用户名。

现在我想在同一个提示框中点击一个按钮，用户将再次被重定向到注册页面signup.html。

我无法弄清楚如何做到这一点。我所做的就是这个---

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<script>
prompt("Username already exists\n please enter another username");
</script>
</body>
</html>

Answer 1

https://developer.mozilla.org/en-US/docs/Web/API/Window/location

你可以把它放在你喜欢的任何js-script块中。例如

<script>
  function redirectMe(url){
    window.location = url;
  }

  setTimeout(redirectMe('http://stackoverflow.com'}, 3000);
</script>

将在3000ms（= 3s）之后重定向到stackoverflow

Answer 2

使用

window.location.href="signup.html"

参考

JavaScript Window Location

Window open() Method

Answer 3

要检查用户是否已存在于数据库中，您必须制作一些服务器端代码，而不仅仅是javascript（客户端）。

您必须使用AJAX来调用服务器脚本（例如，在PHP或ASP中），发送用户输入的名称。服务器端脚本将通过进行SQL查询来检查数据库，如果是，则返回其对javascript的响应。

以下是使用jQuery的示例：

HTML

Your name : <input type="text" id="username" />
<button id="myButton" value="check if user exists" />

<强> JAVASCRIPT

<script src="https://code.jquery.com/jquery-2.1.3.min.js" type="text/javascript"></script>
<script>
    $(function () {

        //when you will click on your button
        $('#myButton').click(function(){
            //get prompted username
            var username = $('#username').val();
            //check if username exists making AJAX call
            checkUserName(username);
        });

    });

    function checkUserName(name)
    {
        //ajax call to your server-side script
        $.ajax({
            url: 'myscript.php',
            type: 'POST',
            data: 'username='+name,
            success: function (response) {
                //if response is 1, a user with this name already exists
                if(response == 1)
                {
                    alert('user already exists');
                }
                //the name is available
                else
                {
                    //redirect to your "signup.html" page
                    window.location.href="signup.html"
                    alert('name is available');

                }
            }
        });
    }
</script>

<强> PHP

myscript.php

<?php

//you have to secure and check the variable, depending what you will use, mysqli_real_escape_string, or escape properly the received variables
$username = $_POST['username'];

//query example, you have to ajust depending on your database & user table
$sql = 'SELECT COUNT(username) FROM db.user WHERE username = "'.$username.'"';

//exec your query

//if the count returned result is > 0, there is a user with this name, return 1 for example
//else, user with this name does not exist, return 0 for example

if($return == 1)
    echo "1";
else
    echo "0";

exit;

这是主要的想法:)尝试制作一个JSFiddle代码并尝试使用它，如果你有更多的问题，请写在这里！

的问候，
于连

如何从javascript代码段重定向到html页面？

3 个答案: