AJAX通话仅工作一次 [英] AJAX calls only working once

问题描述

这是我的代码:

<script type="text/javascript">
    $(document).ready(function() {
      $('#username').change(check_username);
    });

    function check_username() {
      $("#check_username").html('<img src="images/site/ajax-loader.gif" />username avilable??').delay(5000);
      var usernametotest = $('#username').val();    
      $.post("backend/username_available.php", { username: usernametotest})
       .done(function(data) {
         $("#check_username").replaceWith(data);
       });
    }
</script>

我使用此代码通过AJACX检查表单中用户名的可用性. 它工作完美，但只有一次.当用户名被占用并且我更改了用户名时，在第一个用户名之后没有进行AJAX检查吗?文本用户名已经存在"(在变量数据中)不会被用户名确定"代替.

I use this code for checking with AJACX the availability of a username in my form. It works perfect but just once. When an username is occupied and I change the username, no AJAX checks are done after the first one? The text "username already exists" (in the variable data), is not replaced by "username ok".

此JavaScript添加在</html>标记之前.

This JavaScript is added just before the </html> tag.

推荐答案

您的代码看起来不错-请参见 jsfiddle 并在usernametotest值上发出警报，以提高可见度

Your code looks fine - see this jsfiddle with an alert on the usernametotest value for more visibility

$(document).ready(function() {
    $('#username').change(check_username);
});

function check_username(){

    $("#check_username").html('username avilable??').delay(5000);
    var usernametotest = $('#username').val();

    alert('posting username ' + usernametotest);

    $.post("backend/username_available.php", { username: usernametotest} )
        .done(function(data) {
            $("#check_username").replaceWith( data );
        });  
}

每次都使用正确的有效负载发出发布请求，因此在那里没有问题(请检查浏览器开发者工具，例如Chrome中的网络"标签/XHR)

The post requests are being made every time with the correct payload, so no problems there (check browser developer tools e.g. Network tab / XHR in Chrome)

从backend/username_available.php返回的响应一定是一个问题吗?检查第一个请求与其他请求的响应，然后发现它们之间的差异，从而使问题可能会突然出现.

Must be an issue with the response coming back from backend/username_available.php? Check the response of the first request vs the rest, and the difference and hence the problem will probably jump out at you.

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