Constant width italic
Is used for the names of function parameters, and generally as a placeholder to
indicate an item that should be replaced with an actual value in your program. (查看原文)
This is a particularly easy way to play around with JavaScript,
and I recommend that you use it as you read this book.
用这种方式来调试JavaScript既简单又实用，这里强烈推荐读者使用这种方式来辅助你阅读本书。 (查看原文)
A similar but more
intrusive way to display output or debugging messages is by passing a string of text to
the alert() function, which displays it in a modal dialog box.
同样，也可以通过给alert()函数传入一段文本来弹出一个对话框，但这种输出调试信息的方法更具侵入性。 (查看原文)
