1

我正在尝试在 do while 循环中发送多个帖子，但未添加结果

<script type="text/javascript">
function action() {
    var initval = 1;
    var endval = 5;
    do {
    var action_string = 'txtuser=someone';

    $.ajax({
                    type: "POST",
                    url: "http://localhost/js.php",
                    data: action_string,
                    success: function(result){
                       $('div#append_result').append(initval + ',<br/>');
                     }  
                });
    initval++;
     } while (initval <= endval);
  }
</script>

输出为：5, 5, 5, 5, 5,

我需要输出为：1、2、3、4、5，

4

3 回答 3

6

由于 AJAX 的异步特性，当您的成功函数针对任何生成的 AJAX 请求运行时，循环已完成并initval设置为 5。您需要捕获initval每个请求开始时的状态并使用捕获的状态方法中的状态success()。关闭值是最简单的方法：

function action() {
    var initval = 1;
    var endval = 5;
    do {
        var action_string = 'txtuser=someone';

        ( function( captured_initval ){
            $.ajax({
                type: "POST",
                url: "http://localhost/js.php",
                data: action_string,
                success: function(result){
                    $('div#append_result').append(captured_initval + ',<br/>');
                }  
            });
        }( initval ) );

        initval++;
    } while (initval <= endval);
}

但是，请理解，一个或多个请求可能会在服务器上挂起，从而允许后一个请求首先完成，这可能会导致1, 2, 5, 3, 4或类似的结果。

Also, using an element's ID is much faster than prefixing the hash selector with the elements tag name. Plus you should avoid re-querying the DOM for your result DIV every time the success runs. Grab it once and use it when needed:

function action() {
    var initval = 1;
    var endval = 5;
    do {
        var action_string = 'txtuser=someone',
            $AppendResult = $('#append_result');

        ( function( captured_initval ){
            $.ajax({
                type: "POST",
                url: "http://localhost/js.php",
                data: action_string,
                success: function(result){
                    $AppendResult.append(captured_initval + ',<br/>');
                }  
            });
        }( initval ) );

        initval++;
    } while (initval <= endval);
}
于 2011-08-05T03:56:54.827 回答
3

The Ajax request is asynchronous, which means by the time the success handler returns, the loop is already completed. Instead, you can create a closure to preserve the value:

success: (function(i){
    return function() {
         $('div#append_result').append(i + ',<br/>');
    }
})(initval)
于 2011-08-05T03:58:03.277 回答
2

This is because of the async behavior of ajax: Here is a modified version:

var initval = 1;
var endval = 5;
function action(){
    var action_string = 'txtuser=someone';
    $.ajax({
        type: "POST",
        url: "http://localhost/js.php",
        data: action_string,
        success: function(result){
           $('div#append_result').append(initval + ',<br/>');
           initval++;
           if(initval<=endval)
            action();
        }  
    });
 }

This is now somewhat a sequential approach. Note: I assumed every ajax request returns success, if there is an error, you should handle them on the error callback.

于 2011-08-05T04:00:56.393 回答