javascript - 如何测试 jQuery 和某些其他脚本是否已加载？

Question

我知道 document.ready() 但我不想等待外部服务器上的某些内容（例如 Google Analytics）、某些广告服务内容或网站并非绝对需要的任何其他内容。我在有用户评论的网站上看到了这个问题，通常每个外部内容都必须在评论可用之前加载，即使许多 CDN 中的一个迟到了，它也会阻止其他所有内容。

Answer 1

I don't think you need to test it as much as you need to defer it. Here is a really simple example from Google.

(the following code copied from Google)

 // Add a script element as a child of the body
 function downloadJSAtOnload() {
     var element = document.createElement("script");
     element.src = "deferredfunctions.js";
     document.body.appendChild(element);
 }

 // Check for browser support of event handling capability
 if (window.addEventListener)
     window.addEventListener("load", downloadJSAtOnload, false);
 else if (window.attachEvent)
     window.attachEvent("onload", downloadJSAtOnload);
 else window.onload = downloadJSAtOnload;

Essentially, add a new script tag at the documentReady state when you're executing your code already.