请问这个正则表达式/\b([a-z]+) \1\b/gim 里 " \1",m是什么意思?
在正则表达式中“向后引用”这一节里有这么一个例子:
var ss = "Is is the cost of of gasoline going up up?.\n";
var re = /\b([a-z]+) \1\b/gim;
var rv = ss.replace(re,"$1");
最后输出rv得到如下:
Is the cost of gasoline going up?
但我不明白:
([a-z]+) \1 这匹配什么呀,m又是什么意思呢,$1呢?