1

I'm trying to code a quiz with TypeScript. The questions that are asked should be picked randomly and I'm using the Fisher-Yates Shuffle to do that – but it won't shuffle them.

What am I doing wrong? The Fisher-Yates Shuffle appears after the questions.

interface Question {
    questionText: string;
    answers: [string, string, string, string],
    correctAnswerIndex: number
}
const questions: Question[] = [
    {
        questionText: 'Wie viele Lichtminuten ist die Sonne weg?',
        answers: ['1', '3', '6', '8'],
        correctAnswerIndex: 3
    }
   ]
const question = (Question: any) => {
    for (let i = Question.length -1; i > 0; i--) {
        const j = Math.floor(Math.random() * (i + 1));
        const temp = Question[i];
        Question[i] = Question[j];
        Question[j] = temp;
    }
    return Question;
    };


const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});
rl.on("close", function () {
    console.log("\nBYE BYE !!!");
    process.exit(0);
});
const askQuestion = (question: string) => new Promise<string>(resolve => rl.question(question, resolve));


async function main() {
    let correctAnswerCount=0;
    for (const question of questions.slice(0, 5)) {
        console.log(question.questionText);
        let i = 0;
        for (const answer of question.answers) {
            console.log(String.fromCharCode(97 + i) + ') ' + answer);
            i++;
        }
        
        const answer = await askQuestion("Richtige Antwort hier eingeben: ");
        if (answer === String.fromCharCode(97 + question.correctAnswerIndex)) {
            correctAnswerCount++;
            console.log('Richtig ')
           }
           
        else {
            console.log('Falsch ;(')
        }
        console.log("\n\n")
        
    }
    console.log('Score: '+ correctAnswerCount*1000000);
    rl.close()
    
}
main();
Liam
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FourJan
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    where do you call the shuffle? And don't name everything `question` – rioV8 Feb 02 '21 at 11:49
  • You're right, sorry, I'm fairly new to this. I'll try to call it. – FourJan Feb 02 '21 at 11:59
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    Do you name your variables `const question = (Question: any) => {` like your interface `interface Question {` to confuse others or to confuse yourself? Why is this variable not of type `Question`? Why would a question not be a question? – Thomas Sablik Feb 02 '21 at 13:52

1 Answers1

-1

You did define a function const question = (Question: any) => { but you never called it!

Fix the variable names to not confuse everyone reading the code:

function shuffle<T>(arr: T[]): T[] {
    for (let i = arr.length -1; i > 0; i--) {
        const j = Math.floor(Math.random() * (i + 1));
        const temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }
    return arr;
}

Then, use it like

async function main() {
    shuffle(questions);
//  ^^^^^^^^^^^^^^^^^^^
    let correctAnswerCount = 0;
    for (const question of questions.slice(0, 5)) {
        console.log(question.questionText);
        …
Bergi
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  • Just out of curiosity, I noticed a lot of fisher-yates examples including yours seem to define i with the length of the array and then work backwards. – evilsushi Dec 03 '21 at 05:57
  • @evilsushi Yes, that's how fisher-yates works. Of course, you can iterate the other way round, but then you have to find `const j = i + Math.floor(Math.random() * (arr.length - i))` which is more complicated. – Bergi Dec 03 '21 at 07:38