javascript正则表达式拆分产生太多项目 [英] javascript regex split produces too many items

问题描述

我正在尝试使用逗号或空格分割字符串。逗号可以选择在空格之前和/或之后，空格本身也可以作为分隔符。代码如下所示：

I'm trying to split a string using either commas or whitespace. A comma can optionally be preceded and/or followed by whitespace, and whitespace by itself also counts as a delimiter. The code looks like this:

var answers= s.split(/(\s*,\s*)|\s+/);

如果 s 包含字符串'ab， c'，我得到一个包含五个项目而不是预期三个项目的列表（数组）：

If s contains the string 'a b,c', I get a list (array) containing five items instead of the expected three:

0：a，1：undefined，2 ：b，3：,, 4：c

0:a, 1:undefined, 2:b, 3:,, 4:c

任何关于我做错的建议都将不胜感激。

Any advice as to what I'm doing wrong will be appreciated.

Phillip

推荐答案

那是因为 split 也推捕获组到结果数组：

That's because split does also push capturing groups to the result array:

如果separator是包含捕获括号的正则表达式，则每次匹配时，捕获括号的结果（包括任何未定义的结果）都会拼接到输出数组中。

If separator is a regular expression that contains capturing parentheses, then each time separator is matched the results (including any undefined results) of the capturing parentheses are spliced into the output array.

s a 和 b 之间的速度与空白匹配，因此捕获组未定义。 b 和 c 之间的逗号与组匹配，因此它成为数组的第四项。

The space between a and b was matched by the whitespace, so the capturing group was undefined. The comma between b and c was matched by the group, so it became the fourth item of your array.

要解决此问题，只需删除捕获组：

To solve the issue, just remove the capturing group:

var answers = s.split(/\s*,\s*|\s+/);

如果你有一个更复杂的表达式，你需要分组，你可以让它像这样非捕获：

If you had a more complex expression where you needed grouping, you could make it non-capturing like this:

var answers = s.split(/(?:\s*,\s*)|\s+/);

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