why regular expression .*? only match an empty string in javascript?

Question

/.*?/.exec("abc");//output [""]

I think .*? is non-greedy and it should return a

Answer 1

Well that is expected since .* means 0 or more and by putting ? you make it non-greedy hence it match an empty string.

If you want to match a then you should use:

 /.+?/.exec("abc");

DIfference is + instead of * which means match 1 or more characters using non-greedy quantifier.

Answer 2

通过使用*代替eg +您允许将空字符串作为非贪婪选项进行匹配。