正则表达式测试
正则实时测试：6 种 flag、匹配逐个高亮、命名/编号捕获组面板、无效正则给出原因。
g global
i ignore case
m multi-line
s dotAll
u unicode
y sticky
Matches appear here…
Notes
Highlighting wraps each match in <mark>; overlapping zero-width matches are shown safely. The capture table lists named and numbered groups for every match (empty groups render as ∅). JavaScript regex flavour applies — lookbehind, lookahead, backreferences and named groups all work; catastrophic patterns can lock a tab just like in Node, so mind nested quantifiers on long inputs.
如何使用正则表达式测试
输入正则、用 chips 开关 flag、下方粘贴样本：匹配在预览区实时高亮，捕获组列在下方。g/m flag 会改变结果集，命名组按标签展示——比在控制台反复打印快得多。
关注灾难性回退的信号：嵌套量词的正则随文本变长明显变慢，就该用原子组或改变替换结构重写。锚点（^ $）与多行 flag 的交互在这里立即可见。