[рони]

Lammitta,
у вас скорее конструкция if а не switch --- switch проверяет значение а не условия

var number= prompt("Write your number",7);
 number = number%2;
 switch (number){
 case (0):
 alert("even number");
 break;
 case (1):
 alert("Your number is don't even ");
 break;
 default:
 alert("you do not put in the console!");
 }