javascript - 如何通过不重写相同的捕获组来简化正则表达式？

Question

输入文字:

周一至周五上午 6:00 至晚上 8:00

周六至周日上午 6:30 至晚上 8:00

我需要匹配粗体文本，因此以下正则表达式:

(Monday|Tuesday|Wednesday|Thursday|Friday|Saturday|Sunday) (to) (Monday|Tuesday|Wednesday|Thursday|Friday|Saturday|Sunday)

如何通过避免重写 (Monday|Tuesday|Wednesday|Thursday|Friday|Saturday|Sunday) 捕获组两次来简化正则表达式？

Answer 1

您可以定义一个字符串片段替换，然后重用它:

var input = "Monday to Friday 6:00 a.m. to 8:00 p.m.";
var alt = "(Monday|Tuesday|Wednesday|Thursday|Friday|Saturday|Sunday)";
var re = new RegExp("^" + alt + " (to) " + alt + ".*$");
if (re.test(input)) {
    console.log("valid");
}
else {
    console.log("invalid");
}