而当我告诉它在JavaScript循环就不会结束 [英] While loop won't end when I tell it in JavaScript

问题描述

       var hasData = '1';
        while (hasData != 0) {
            $.ajax({
            url: '/ajax.php?updateRow='+hasData,
            dataType: 'json',
            async: false,
            success: function(data) {
                hasData = data.next;
                $('.result').append(data.html);
              }
            });

会发生什么情况： JSON数组从PHP拉（[HTML]和[下一步]）。如果[下一页]设置为0（当没有更多的条目） - while循环停止，这应该是它

What should happen: JSON Array pulled from PHP ( [html] and [next] ). If [next] is set to 0 (when there are no more entries) - the while loop stops and that should be it.

什么happends： 一切应，除 - 当同时（）要求得到满足（因此当hasData设置为0） - 环进入无限循环（和它保持请求的最后一个条目，永远...直到脚本变为不响应）

What happends: Everything that should, except - when the while() requirement is met (so when hasData is set to 0) - the loop enters into an infinite loop (and it keeps requesting the last entry, forever...until the script becomes "unresponsive")

推荐答案

AJAX 发送一个请求，并执行回调时，有一个回应。那么什么情况是：

ajax sends a request and executes the callback when there is a response. So what's happening is:

• 消防的要求
• 在消防另一个请求
• 在消防另一个请求
• 在消防另一个请求
• ...

因为它是一个while循环中。你堵塞你的脚本了请求，服务器得到了一堆要求它有可能无法处理的。

because it's inside a while loop. You're clogging your script up with requests, and the server gets a bunch of requests which it probably cannot handle.

编辑：对不起，我错过了异步：假。然而，每每让浏览器irresponsive。这样做将使用异步的最好的事情：真正的和消防另一个，如果条件是这么说的，但只有在你得到的回应：

I'm sorry, I missed async: false. However that always makes the browser irresponsive. The best thing to do would be using async: true and fire another if the conditional says so, but only after you get the response:

function check() {
        $.ajax({
        url: '/ajax.php?updateRow='+hasData,
        dataType: 'json',
        async: true,
        success: function(data) {
            hasData = data.next;
            $('.result').append(data.html);
            if(hasData != 0) check(); // do it again
          }
        });
}

check(); // fire the first request

由于Spycho指出，因为你获取JSON，一个更方便的方法可能是：

As Spycho pointed out, since you're fetching JSON, a more convenient way might be:

(function() {

    var fireRequest = function() { // this function is not available anywhere else,
                                   // to avoid having this process running more than once

        $.getJSON('/ajax.php', {updateRow: hasData}, function(data) {
            hasData = data.next;
            $('.result').append(data.html);
            if(hasData != 0) fireRequest(); // do it again
        });

    };

    fireRequest(); // start the process

})(); // call it

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