如何使用Regex和javascript过滤？-HowtofilterusingRegexandjavascript?

document.evaluate("//span[@class='discount']", 
  document, 
  null, 
  XPathResult.ANY_UNORDERED_NODE_TYPE, 
  null).singleNodeValue.textContent.replace("now $", "");

EDIT: This is standard XPath. I'm not sure what kind of explanation you're seeking. For outdated browsers, you will need a third-party library like Sarissa and/or Java-line.

编辑:这是标准的XPath。我不确定你在寻求什么样的解释。对于过时的浏览器,您需要第三方库,如Sarissa和/或Java-line。

Regexes are fundamentally bad at parsing HTML (see Can you provide some examples of why it is hard to parse XML and HTML with a regex? for why). What you need is an HTML parser. See Can you provide an example of parsing HTML with your favorite parser? for examples using a variety of parsers.

正则表达式在解析HTML方面基本上是不好的(参见你能提供一些为什么难以用正则表达式解析XML和HTML的例子吗?)。你需要的是一个HTML解析器。请参阅您是否提供了使用您喜欢的解析器解析HTML的示例?例如,使用各种解析器。

Patrick McElhaney's and Matthew Flaschen's answers are both good ways to solve the problem.

Patrick McElhaney和Matthew Flaschen的答案都是解决问题的好方法。

as Matthew Flaschen suggested, XPATH is a better way to go, if you know something about the node structure of the target document (and since you provided an example, you seem to). If you don't know the node structure, regexes are still lousy for parsing XML.

正如Matthew Flaschen所说,如果您对目标文档的节点结构有所了解,那么XPATH是一种更好的方法(并且因为您提供了一个示例,您似乎)。如果您不知道节点结构,那么正则表达式在解析XML时仍然很糟糕。

some more resources to kick-start you:

一些更多的资源来启动你:

• XPath in Javascript: Introduction

Javascript中的XPath:简介

• DOM Parsing With XPath and Javascript

DOM解析XPath和Javascript

• Mozilla dev-center: Introduction to using XPath in Javascript

Mozilla开发中心:在Javascript中使用XPath的简介

I've also found the FireFox extension combo of DOM Inspector and XPather to be an invaluable tool for deriving and testing XPath expressions on a given page. (If you're using another browser -- well, I don't know).

我还发现DOM Inspector和XPather的FireFox扩展组合是一个非常有用的工具,用于在给定页面上派生和测试XPath表达式。 (如果您正在使用其他浏览器 - 嗯,我不知道)。