正则表达式：为什么匹配的是ab而不是a啊

Question

vars='Hi,doyou(know)yourabcs?';
constregex1=/ab?/gi;
console.log(regex1.exec(s));

Answer 1

vars='Hi,doyou(know)yourabcs?';constregex1=/ab??/gi;console.log(regex1.exec(s));

Answer 2

是ab而不是abc？因为理应是ab……'...abc.'.match(/ab.?/gi)才为abc补充：/ab??/非贪婪模式下结果为"a"