将多个参数/参数附加到 jsonp 回调函数 [英] Appending multiple parameters/arguments to a jsonp callback function

问题描述

如何指定更多参数传递给 jsonp 回调函数?

How do I specify more arguments to be passed to a jsonp callback function?

例如，我正在尝试抓取 youtube 视频数据:

For example, I'm trying to grab youtube video data:

http://gdata.youtube.com/feeds/api/videos/gzDS-Kfd5XQ?v=2&alt=json-in-script&callback=youtubeFeedCallback

将被调用的 javascript 回调函数是 youtubeFeedCallback，它在调用时只包含一个参数.

The javascript callback function that will be called is youtubeFeedCallback and it contains only one argument when called.

截至目前，该功能将是这样的，

As of now the function would be something like this,

function youtubFeedCallback(response) {
...
}

我希望能够做的是像这样传递第二个参数，

What I would like to be able to do is pass a second argument like this,

function youtubeFeedCallback(response, divId) {
...
}

这可以吗.我试过在网上到处找，但找不到任何东西.谢谢！

Is this possible to do. I've tried looking everywhere online and couldn't find anything. Thanks!

推荐答案

您不能像那样向回调函数添加参数.但是，您可以生成包装函数.JSONP 回调函数只是默认命名空间中的一个函数，这意味着您只需要将一个已知名称的生成函数添加到全局 window 对象中.第一步是起名字:

You can't add arguments to the callback function like that. However, you can generate a wrapper function. The JSONP callback function just was to be a function in the default namespace, that means that you just need to add a generated function with a known name to the global window object. Step one is to make up a name:

var callback_name = 'youtubeFeedCallback_' + Math.floor(Math.random() * 100000);

在现实世界中，您希望将其包装在一个循环中并检查 window[callback_name] 是否尚未被占用；你可以使用 window.hasOwnProperty(callback_name) 检查.有了名字后，你就可以构建一个函数了:

In the real world you'd want to wrap that in a loop and check that window[callback_name] isn't already taken; you could use window.hasOwnProperty(callback_name) to check. Once you have a name, you can build a function:

window[callback_name] = function(response) {
    youtubeFeedCallback(response, divId);
};

不过，您可能还想再提高一点:

You'd want to that up a little bit more though:

function jsonp_one_arg(real_callback, arg) {
    // Looping and name collision avoidance is left as an exercise
    // for the reader.
    var callback_name = 'jsonp_callback_' + Math.floor(Math.random() * 100000);
    window[callback_name] = function(response) {
        real_callback(response, arg);
        delete window[callback_name];  // Clean up after ourselves.
    };
    return callback_name;
}

一旦你有类似的东西，你可以打电话:

Once you have something like that wired up, you could just call:

jsonp = jsonp_one_arg(youtubeFeedCallback, divId);

然后使用 jsonp 的值作为 YouTube URL 中的 callback 值.

And then use the value of jsonp as the callback value in the YouTube URL.

您也可以构建更多这样的函数来处理更长的参数列表.或者您可以使用 arguments 和 apply.

You could build more functions like this to handle longer arguments lists too. Or you could build a general purpose one with arguments and apply.

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