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嵌入内联JS脚本而不是发出AJAX请求。为什么？

[英]Embedding inline JS script instead of making an AJAX request. Why?

原文 2010-07-27 15:11:53 7 4 javascript/ ajax

I noticed that some websites (for example: apple.com or disqus.com) don't send AJAX request to load, for example, live search results. 我注意到一些网站（例如：apple.com或disqus.com）不发送加载的AJAX请求，例如，实时搜索结果。 Instead they attach new JS script, that holds all results in a variable. 相反，他们附加新的JS脚本，将所有结果保存在变量中。

To be more specific. 更具体。 If you go to apple.com and type "test" into the searcher. 如果你去apple.com并在搜索器中输入“test”。 It won't send an AJAX request to get the results, instead it will add < script src="some.addres.apple.com/result.js?q=test" > to the HTML and execute new piece of JS script to bring in the search results. 它不会发送AJAX请求来获取结果，而是将<script src =“some.addres.apple.com/result.js?q=test”>添加到HTML并执行新的JS脚本引入搜索结果。 improvement Are they doing this only because you can't send AJAX request to a different domain, or is there any speed improvement possible? 改进他们是否这样做只是因为您无法将AJAX请求发送到其他域，或者是否可以提高速度？

4 个解决方案

This approach called jsonp. 这种方法称为jsonp。 Instead of calling ajax request script appends new script tag that contains data wrapped into callback function (like onComplete callbacks for ajax calls). 而不是调用ajax请求脚本会附加新的脚本标记，其中包含包含在回调函数中的数据（如ajax调用的onComplete回调）。 It helpful in cases when you need request to another domain. 当您需要其他域请求时，它很有用。 Otherwise (in my opinion) ajax calls preferable, eg it has has proper error , success and timeout callbacks. 否则（在我看来）ajax调用更可取，例如它有正确的error ， success和超时回调。

more about Jsonp 更多关于Jsonp的信息

There is a lot of discussion online of the "hackishness" of JSONP: 网上有很多关于JSONP“hackishness”的讨论：

I have found it to be extremely useful in getting around cross-domain security limitations but I have not seen nor have I heard of any speed improvements. 我发现它在解决跨域安全限制方面非常有用，但我没有看到，也没有听说过任何速度改进。

I highly recommend learning more about JSONP (especially when it is useful/necessary). 我强烈建议您学习更多有关JSONP的知识（尤其是在有用/必要时）。

One of the main advantages of the JSONP technique is that since now your search functionality is being served from a different server and you have gone ahead and taken the pain to develop a JSONP response mechanism, You can go ahead and embed that search wherever you want. JSONP技术的一个主要优点是，从现在开始，您的搜索功能是从不同的服务器提供的，并且您已经开始努力开发JSONP响应机制，您可以继续将搜索嵌入到您想要的任何位置。

So in your particular example, Apple can use the same search (if it encapsulates their other ecosystems as well) to serve results maybe for example on another sister website. 因此，在您的特定示例中，Apple可以使用相同的搜索（如果它也包含其他生态系统）来提供结果，例如在另一个姐妹网站上。

In terms of performance, As pointed out by @fantactuka, AJAX calls are preferrable according to me also as script injection is costly and provides less ways to handle when stuff goes wrong. 在性能方面，正如@fantactuka所指出的，AJAX调用对我来说也是优选的，因为脚本注入代价高昂，并且在出现错误时提供更少的处理方法。

我相信这是一种解决浏览器强加的限制的方法，请求必须指向加载页面的同一台服务器。