My solution

var score = 0;

var question1 = prompt("What is the name of CEO SpeceX?");
if ( question1.toLocaleUpperCase() === "ELON MUSK" ) {
  score += 1;
}

var question2 = prompt("What is the name of main character from 'The Witcher' ?");
if ( question2.toLocaleUpperCase() === "GERALT" ) {
  score += 1;
}

var question3 = prompt("What is the name of King of the Mordor?");
if ( question3.toLocaleUpperCase() === "SAURON" ) {
  score += 1;
}

var question4 = prompt("What is the surname of the most popular Jedi in 'Star Wars'?");
if ( question4.toLocaleUpperCase() === "SKYWALKER" ) {
  score += 1;
}

var question5 = prompt("What is the name of Lord of The Rings author?");
if ( question5.toLocaleUpperCase() === "TOLKIEN" ) {
  score += 1;
}

if ( score === 5 ) {
  alert(`You answered ${score} question and earned gold crown!`);
} else if ( score === 3 || score === 4) {
  alert(`You answered ${score} question and earned silver crown!`);
} else if ( score === 2 || score === 1 ) {
  alert(`You answered ${score} question and earned bronze crown!`);
} else {
  alert(`You answered ${score} question. Better luck next time!`);
}