var email = "grepper@gmail.com";
if(email.includes("@")){
console.log("Email is valid");
}
else{
console.log("Email is not valid");
}
// includes return boolean, if your string found => true else => false
bigstring.includes("string") // return true or false
let text = "Hello world, welcome to the universe.";
let result = text.includes("world"); // return boolean value