Javascript React From服务中的条件语句

所以我要做的是在一个条件下，如果logged.getfirstName和logged.getlastName值为空，则显示电子邮件行。我如何在react中写一个条件来解决这个问题

return (
      <>
        {logged && (
          <Typography
            variant="h5"
            color="secondary"
            className={classes.headline}
          >
            Welcome back{" "}
            <b>
              {logged.get("firstName")} {logged.get("lastName")}
            </b>
            <b> {logged.get("email")} </b>
          </Typography>
        )}

---

您可以使用如下所示的内联条件

{ 
   logged.get("firstName") == null 
         && logged.get("lastName") == null ?
   <b> {logged.get("email")} </b> : null
}

---

您可以使用如下所示的内联条件

{ 
   logged.get("firstName") == null 
         && logged.get("lastName") == null ?
   <b> {logged.get("email")} </b> : null
}

{logged.getfirstName.length>0&&logged.getlastName.length>0&&logged.getemail}

{logged.getfirstName.length>0&&logged.getlastName.length>0&&logged.getemail}

{ logged.get("firstName") && logged.get("lastName")
  ? <b>
     {logged.get("firstName")} {logged.get("lastName")}
    </b>
  : <b> {logged.get("email")} </b>

}