var test = "<span>123123<?JS1231231</span>2JS?>123123<?JS12JS?><span>3</span><?JS13JS?>";
var reg = new RegExp("<\\?JS(.*?)JS\\?>", "g");

test.replace(reg, function(element) {
    alert(element);
});

var test = "<span>123123<?JS123123\n1</span>2JS?>123123<?JS12JS?>\r\n<span>3</span><?JS \n13JS?>";
var reg = new RegExp("<\\?JS(.*?)JS\\?>", "g");
test.replace(reg, function(element) {
    alert(element);
});

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String test = "<span>123123<?JS123123\r\n1</span>2JS?>123123<?JS12JS?>\r\n<span>3</span><?JS \n13JS?>";
        Pattern pattern = Pattern.compile("<\\?JS.*?JS\\?>", Pattern.DOTALL); 
        Matcher matcher = pattern.matcher(test);   
        while(matcher.find()) {   
            System.out.println(matcher.group(0).trim());   
        }
    }
}

var reg = new RegExp("<\\?JS([\\S\\s]*?)JS\\?>", "g");

------解决方案--------------------

探讨


JScript code
var reg = new RegExp("<\\?JS([\\S\\s]*?)JS\\?>", "g");

这个跟多行标志m没有关系的
m是表示每一个换行的行 都能用 ^匹配开头  用 $匹配结尾

java中的 .可能可以匹配换行。但javascript中的 .不匹配换行符。他匹配换行符以外的任何字符


------解决方案--------------------
var reg = new RegExp("<\\?JS([\d\D]*?)JS\\?>", "g");