中文摘要：

随着互联网和万维网的流行以及JavaScript在web浏览器中的作用越来越重要，对JavaScript程序的执行行为的研究将有利于提高浏览器的性能，改善用户的体验．传统的研究认为JavaScript语言的动态性是其性能的主要瓶颈，因此大部分主流的JavaScript执行引擎都将优化集中在其动态性的处理上．为了更深入的研究JavaScript程序的动态性，提出了两种算法：类型预测算法和基于位置的内联缓存算法，分别用于处理JavaScript程序中元数据和对象的类型．以这些算法为基础，在SunSpider测试程序集上系统地研究了JavaScript的类型系统．实验表明，算法平均能够正确识别或者预测99％的类型实例，因此可以认为，尽管JavaScript语言提供了丰富的动态性，实际的应用程序所使用到的动态行为是有限的．这是已知文献中首次提出类似的观点．

英文摘要：

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