xxxxxx[xxxxxx][7][xxxxxx][9][xxxxx]
\[+[0-9]+\]
(?:.*?(\[+[0-9]+\])){2}
xxxxxx[xxxxxx][7][xxxxxx][9][xxxxx]
\[+[0-9]+\]
(?:.*?(\[+[0-9]+\])){2}
(\[[0-9]+\]\[.*?\])\[([0-9]+)\]
结果=subject.replace(/(\[\d\]\[[^\]+\])\[\d\]/,“$1[replace]”);
(#在backref 1中捕获以下内容: \[\d\]#第一次出现[数字] \[ # [ [^\]]+#除]之外的任何字符序列 \] # ] )#捕获组结束 \[\d\]#匹配第二次出现的[digit]
结果=subject.replace(/(\[\d\](?:\[[^\]]+\])*?)\ [\d\]/,“$1[替换]”);