SyntaxError: Unexpected token { in rock paper scissors

I'm getting the error "SyntaxError: Unexpected token {" and i don't know why, since everythin seems pretty right ! Could you help me ?

var userChoice = prompt("Choose: rock, paper or scissors?");

var computerChoice = Math.random();

if(computerChoice >= 0 && computerChoice <= 0.33){
    computerChoice === "rock";
} 

else if (computerChoice >= 0.34 && computerChoice <= 0.66){
    computerChoice === "paper";
} 

else (computerChoice >= 0.67 && computerChoice <= 1){
    computerChoice === "scissors";
}