❓Что будет на выходе?

var str="dogs cats sheeps car bar star"
var re1=/\b\w+(?:s|ar)\b/g
var re2=/\b\w+(?:s|ar)\b/
var re3=/\b\w+(s|ar)\b/
console.log( str.match(re1) )  
console.log( str.match(re2) )  
console.log( str.match(re3) )

Ответ:
[ 'dogs', 'cats', 'sheeps', 'car', 'bar', 'star' ]
[
'dogs',
index: 0,
input: 'dogs cats sheeps car bar star',
groups: undefined
]
[
'dogs',
's',
index: 0,
input: 'dogs cats sheeps car bar star',
groups: undefined
]

JavaScript test | #JavaScript