Answers for "node js check if session exists"

js check if session storage exists

if (localStorage.getItem("username") === null) {
  //...
}

check if session variable exists php

if (isset($_SESSION['errors']))
{
    //Do stuff
}

check if session is set

if (isset($_SESSION["userid"])) {
	echo "Logged in";
} else {
	echo "Not Logged in";
}