addr="/foo/bar/1-2-0-0-2" rpl=function(str, n1, n2){ return str.replace(/\/[\d-]+$/, function(p){return p.replace(/^(\/)\d(-)\d(.*)/, "$1"+n1+"$2"+n2+"$3")}) } alert(rpl(addr, 3, 4)) // /foo/bar/3-4-0-0-2