从Ajax调用中传递一个变量的函数 [英] Pass a variable to a function from inside an ajax call

问题描述

我试图用这个循环读取某些URL阅读他们的修改时间：

I tried to use this loop to read some urls to read their modified time:

var arr = [];

//... fill arr with push

for (var e in arr) {
        nodename=arr[e].hostname;
        node_json="/nodes/"+nodename;
        html +='<a href="'+node_json+'" target="_blank" id="host_'+nodename+'">data</a>';

        xhr = $.ajax({
            url: node_json,
            success: (function(nn) {
                $('#host_'+nn).append("last modified: " + xhr.getResponseHeader("Last-Modified"));
            })(nodename)
        });

这已经运作了一下我我注释掉成功行：我得到调用的所有节点的文件，并在Firebug的，我可以看到在不同的修改时间呼叫的头

This already works a bit i I comment out the success line: I get calls to all node-files, and in Firebug, I can see the different modified times in the header of the calls.

起初，我有一个封闭，（请参阅<一href="http://stackoverflow.com/questions/6487366/how-to-generate-event-handlers-with-loop-in-javascript">How生成具有循环事件处理程序的Javascript？）我只得到了修改与所有结果的最后一行。这就是为什么我试图把动作在一个单独的函数。

At first I had a closure, (see How to generate event handlers with loop in Javascript?) And I only got the last line modified with all results. that's why I try to put the action in a separate function.

但是，这给了：

的ReferenceError：XHR没有定义
  $（'＃主机_'+ NN）.append（最后修改：+ xhr.getResponseHeader（上次修改）......

ReferenceError: xhr is not defined
$('#host_'+nn).append("last modified: " + xhr.getResponseHeader("Last-Modified")...

我如何获得 XHR 进入该功能？

How do I get xhr into that function?

我aslo尝试：

...
        xhr[e] = $.ajax({
            url: node_json,
            success: add_result_to_info(nodename, e)
        });

    }
}
// outside loop
function add_result_to_info(nn, e) {
    $('#host_'+nn).append("last modified: " + xhr[e].getResponseHeader("Last-Modified"));
}

源的AJAX调用的：<一href="http://stackoverflow.com/questions/25062132/get-the-modified-timestamp-of-a-file-with-javascript/25064125?noredirect=1#25064125">Get用JavaScript文件的修改时间戳记 的

推荐答案

如果改编确实是一个数组，只需使用 .forEach 甚至更好 .MAP （对旧的浏览器垫片）封装每次迭代的范围，而不需要额外的关闭：

If arr is truly an array, just use .forEach or even better .map (with a shim on older browsers) to encapsulate each iteration's scope without the need for additional closures:

var xhrs = arr.map(function(e) {
    var nodename = e.hostname;
    var node_json = "/nodes/" + nodename;

    html +='<a href="'+node_json+'" target="_blank" id="host_'+nodename+'">data</a>';

    return $.ajax({
        url: node_json
    }).done(function(data, status, xhr) {
        $('#host_'+nodename).append("last modified: " + xhr.getResponseHeader("Last-Modified"));
    });
});

之所以使用 VAR xhrs = arr.map（）而不是 .forEach 是那么（免费）获得调用另一个回调一次AJAX请求已完成的能力：

The reason to use var xhrs = arr.map() instead of .forEach is that you then (for free) get the ability to call yet another callback once every AJAX request has completed:

$.when.apply($, xhrs).then(function() {
     // woot!  They all finished
     ...
});

这篇关于从Ajax调用中传递一个变量的函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！