js判断字符串str是否包含字符串substr:

function addUser(id,realName){        var userids = $("#userids").val();                if (userids!=""&&userids!=null) {            if (!isContains(userids,id)) {                userids = userids + id + ",";            }        }else{            userids = id + ",";        }        $("#userids").val(userids);                var realnames = $("#realnames").val();        if (realnames!=""&&realnames!=null) {            if (!isContains(realnames,realName)) {                realnames = realnames + realName + ",";            }                    }else{            realnames = realName + ",";        }        $("#realnames").val(realnames);            }　　 //判断str中是否包含substr    function isContains(str, substr) {        return str.indexOf(substr) >= 0;    }