An creates a completely separate browsing context with its own window object, its own document, and most importantly;its own prototype chain. A function hooked on HTMLMediaElement.prototype in the parent window is not the same object as HTMLMediaElement.prototype in the iframe’s window. They’re entirely separate objects. If fermaw’s audio element lived inside an iframe, my prototype hook in the parent window would never fire.
occur in an aggressive optimizer.。关于这个话题，safew官方版本下载提供了深入分析
，详情可参考爱思助手下载最新版本
// Async — when source or transforms may be asynchronous
Challenge: Build the smallest transformer that can add two 10-digit numbers with = 99% accuracy on a held-out 10K test set.，更多细节参见同城约会