// 用户名校验
 checkusernameflag=false;
function checkusername() {
    var username = $("userneme").value;
    var zz = /^[a-za-z0-9]{6,}$/;
    if (!zz.test(username)) {
        $("username_warn").innerhtml = "  × 用户名不符合规范";
        checkusernameflag=false;
    } else {
        /*$("username_warn").style.color='blue';
        $("username_warn").innerhtml = "√ 用户名可用";*/
        showuserexist(username);
        checkusernameflag=true;
    }
}