正则表达式：仅一个下划线实例

Question

I'm looking for a regex pattern that will accept the following:

[foo_bar] or {foo_bar}

Where:

either [ ] or { } acts as wrappers

foo and bar can be anything except _ repeated between 1 to n times

_ should only appear once and should be between foo and bar

Sample matches:

[1Ab_23c]

{abcDefGhjk_Z}

{1_abcDefGhjk}

Sample mismatches:

{1Ab_23c]

{_1Abde_fg4567_2_}

{1Abde_fg4567_2}

1Ab_23c

This is what I have right now but I'm still missing the only one _ part.

 ^{.+_.+}|\\[.+_.+]$ 

I'm guessing that a (?!_).+ should somehow be there but I can't piece them together.

Answer 1

You can use a complemented character set - [^_] (all but underscore):

 const pattern = /\\[[^_]+_[^_]+\\]|\\{[^_]+_[^_]+\\}/; // matches console.log(pattern.test('[1Ab_23c]')); console.log(pattern.test('{1Abdefg4567_2}')); console.log(pattern.test('{1Ab_23c}')); // mismatches console.log(pattern.test('{1Ab_23c]')); console.log(pattern.test('{_1Abde_fg4567_2_}')); console.log(pattern.test('{1Abde_fg4567_2}')); console.log(pattern.test('1Ab_23c'));