我的函数在第一条语句后不返回运行

Question

So I'm making a Rock Paper Scissors function that takes to value and return: win lose or tied but is not returning anything after the first block. Here's my code :

function playRound(playerSelection, computerSelection){

   if(playerSelection === "rock" && computerSelection === "scissors") {
     return "wins";
    }
     else if(computerSelection === "paper") {
       return "lost"  
     }
       else{
       return "tied";
       }



if(playerSelection === "paper" && computerSelection === "rock") {
     return "wins";
    }
     else if(computerSelection === "scissors") {
       return "lost"  
     }
       else{
       return "tied";
       }



   if(playerSelection === "scissors" && computerSelection === "paper") {
     return "wins";
    }
     else if(computerSelection === "rock") {
       return "lost";
     }
       else{
       return "tied";
       }

   }

Answer 1

It's not returning anything because your logic is flawed.

Your logic is (from the first block):

• case 1: playerSelection === "rock" && computerSelection === "scissors"
• case 2: computerSelection === "paper"
• case 3: "everything else"

What I think you meant by your code is to actually have playerSelection === "rock" apply to the entire first block. So, you would need some nested if statements to capture that.

Your revised logic should resemble this:

if ( playerSelection === "rock" ):

• case 1: computerSelection === "scissors"
• case 2: computerSelection === "paper"
• case 3: "everything else"

That being said, your check for "everything else" is a bit repetitive and there are some further optimizations that could be made. That being said, I've optimized the code a bit for you.

function playRound(playerSelection, computerSelection) {
    if (playerSelection === computerSelection) {
        // may be worth validating that rock/paper/scissors were the only possible inputs here
        return "tied";
    }

    switch (playerSelection) {
        case "rock":
            if (computerSelection === "scissors") return "wins";
            if (computerSelection === "paper") return "lost";
            break;

        case "paper":
            if (computerSelection === "rock") return "wins";
            if (computerSelection === "scissors") return "lost";
            break;

        case "scissors":
            if (computerSelection === "paper") return "wins";
            if (computerSelection === "rock") return "lost";
            break;
    }

    // error handling (no match)
    return null;
}