使用字符串变量动态创建RegExps [英] Create RegExps on the fly using string variables

问题描述

说我想让以下内容重复使用：

Say I wanted to make the following re-usable:

function replace_foo(target, replacement) {
   return target.replace("string_to_replace",replacement);
}

我可能会这样做：

function replace_foo(target, string_to_replace, replacement) {
   return target.replace(string_to_replace,replacement);
}

使用字符串文字这很容易。但是，如果我想让正则表达式变得更加棘手呢？例如，假设我要替换所有但 string_to_replace 。本能地，我会尝试通过以下方式扩展上述内容：

With string literals this is easy enough. But what if I want to get a little more tricky with the regex? For example, say I want to replace everything but string_to_replace. Instinctually I would try to extend the above by doing something like:

function replace_foo(target, string_to_replace, replacement) {
   return target.replace(/^string_to_replace/,replacement);
}

这似乎不起作用。我的猜测是它认为 string_to_replace 是一个字符串文字，而不是表示字符串的变量。是否可以使用字符串变量动态创建JavaScript正则表达式？如果可能的话，这样的事情会很棒：

This doesn't seem to work. My guess is that it thinks string_to_replace is a string literal, rather than a variable representing a string. Is it possible to create JavaScript regexes on the fly using string variables? Something like this would be great if at all possible:

function replace_foo(target, string_to_replace, replacement) {
   var regex = "/^" + string_to_replace + "/";
   return target.replace(regex,replacement);
}

推荐答案

new RegExp（string，flags）其中 flags 是 g 或我。所以

'GODzilla'.replace( new RegExp('god', 'i'), '' )

评估为

zilla

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