September 2022
Intermediate to advanced
585 pages
8h 17m
Chinese
Content preview from JavaScript 经典实例：第三版
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浏览器工具
｜
293
function
normalize(string) {
const
normalized = string.replace(/[^\w]/g, "").toLowerCase();
debugger
;
return
normalized;
}
到达断点后，你可以选择以不同的方式执行
JavaScript
代码。
恢复脚本执行
继续执行代码。
跳过
执行一个函数，但不进入函数内部调试。
进入
进入函数内部，进一步调试。
跳出
执行当前函数余下的代码。
步进
步进到下一行代码。
在某一行上设定的断点只是众多断点中的一种类型。除此之外，还可以基于
DOM
变化、条件值、事件监听器、异常和
fetch/XHR
请求设定断点。利用断点可以更好
地控制
JavaScript
调试体验。
11.2
分析运行时性能
11.2.1
问题
JavaScript
代码执行得有点慢或者感觉怪怪的，但是你不确定问题的根源所在。
11.2.2
方案
使用浏览器开发者工具的性能分析功能查找代码中的瓶颈和
CPU
密集型任务（见图
11-2
）。
294
｜
第
11
章
在
Chrome
的开发者工具中分析
JavaScript
代码性能的步骤如下所示。
1.
按
Command-Option-C
（
Macintosh
）或
Control+Shift+C
（
Windows
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.