string的正则式scan

string的正则式scan

"77887".scan(/[7-8]{2}/)
结果是["77","88"]
如果我想得到["77","78","88","87"] 该怎么做? 还是用scan.
无解无解 否则就不是scan了。。。。。。。。吧?
SCAN后面可加一些东西, 也可以不用SCAN, 问题在于一个个地匹配/[7-8]{2}/,

要是不用SCAN可以做到吗?
"XXXXX77887".XXX(/[7-8]{2}/).XXXX.XXXX...
得到
["77","78","88","87"]