[英]Processing different matches in a RegExp
I want to construct a RegExp
that matches either the first letter of the first word, or the first letter of non-first words, but I want to be able to distinguish between these two kinds matches so I can process non-first-word matches differently. 我想构建一个
RegExp
,它匹配第一个单词的第一个字母或非首字母的第一个字母,但我希望能够区分这两种匹配,以便我可以处理非首字匹配不同。
For example I want to always capitalise the first word and all other words apart from instances of "bam" that are not the first word. 例如,我想总是将第一个单词和除“bam”不是第一个单词的实例之外的所有其他单词大写。
How can I do this? 我怎样才能做到这一点?
function titleCase(title) {
return title.replace(/\b(.)/g, (str, p1) => {
return p1.toUpperCase();
});
}
titleCase('foo bar bam'); // Foo Bar Bam - but I want Foo Bar bam
You can put multiple regex pieces together like /(option 1)|(option 2)/g
您可以将多个正则表达式拼凑在一起,如
/(option 1)|(option 2)/g
Then your callback will receive either of: 然后你的回调将收到以下任何一个:
callback(match, option1, undefined, offset, subject) // left side matched
callback(match, undefined, option2, offset, subject) // right side matched
Using this, your callback can look like: 使用此功能,您的回调可能如下所示:
(str, p1, p2) => {
if( p1) ...
else if( p2) ...
}
Here is an implementation of titleCase
which will capitalize the first letter of every word-like element in the string. 这是
titleCase
一个实现,它将大写字符串中每个类似字的元素的第一个字母。
function titleCase(title) {
return title.replace(/\b(\w)(.*?)\b/g, (match, g1, g2) => `${g1.toUpperCase()}${g2}`)
}
/\\b(\\w)(.*?)\\b/g
will match a word boundary ( \\b
) followed by a word character ( \\w
). /\\b(\\w)(.*?)\\b/g
\\b
( \\w
)(。*?) \\b
/\\b(\\w)(.*?)\\b/g
将匹配单词边界( \\b
),后跟单词字符( \\w
)。 We capture the first letter using the grouping (\\w)
, and is used as g1
in the replace function. (\\w)
捕获第一个字母,并在replace函数中用作g1
。 (.*?)
, which is referenced using g2
in the replacer. (.*?)
捕获单词的剩余部分,该组在替换器中使用g2
引用。
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