说明：  本书通过对JavaScript语言的分析，甄别出好的和坏的特性，从而提取出相对这门语言的整体而言具有更好的可靠性、可读性和可维护性的JavaScript的子集，以便你能用它创建真正可扩展的和高效的代码。
(Through the analysis of the JavaScript language, this book identifies the good and bad features and extracts a subset of JavaScript that is more reliable, readable and maintainable than the language as a whole, so that you can use it to create really scalable and efficient code.)