Make sure a sum is asked only once (js)

Question

I have a multiplication game and I want a random number 12 times but how can I get that without it getting a number repeated. This is what I've tried but I keep getting 'Undefined' returned. (I'm using Firefox 51.0.1)

$(".input").val("");
var numbers_used = [];
var current_number = 0;
var max_num = 12;
var base_number = parseInt(prompt("Enter which table you want to practice.", "5"));
var maxScore = 12;
var questionsAnswered = 0; 
var questionsAnsweredCorrect = 0;
var questionsAnsweredWrong = 0;
var asked1 = false;
var asked2 = false;
var asked3 = false;
var asked4 = false;
var asked5 = false;
var asked6 = false;
var asked7 = false;
var asked8 = false;
var asked9 = false;
var asked10 = false;
var asked11 = false;
var asked12 = false;

function new_random_number() {
    var new_current_number = Math.round(Math.floor((Math.random() *     max_num) + 1)); 
    return new_current_number;
}

function overallNumber() {
current_number = new_random_number();

if((current_number == 1 && !asked1) ||
   (current_number == 2 && !asked2) ||
   (current_number == 3 && !asked3) ||
   (current_number == 4 && !asked4) ||
   (current_number == 5 && !asked5) ||
   (current_number == 6 && !asked6) ||
   (current_number == 7 && !asked7) ||
   (current_number == 8 && !asked8) ||
   (current_number == 9 && !asked9) ||
   (current_number == 10 && !asked10) ||
   (current_number == 11 && !asked11) ||
   (current_number == 12 && !asked12) 
  ){

   if(current_number == 1)
    asked1 = true;

    if(current_number == 2)
    asked2 = true;

    if(current_number == 3)
    asked3 = true;

    if(current_number == 4)
    asked4 = true;

    if(current_number == 5)
    asked5 = true;

    if(current_number == 6)
    asked6 = true;

    if(current_number == 7)
    asked7 = true;

    if(current_number == 8)
    asked8 = true;

    if(current_number == 9)
    asked9 = true;

    if(current_number == 10)
    asked10 = true;

    if(current_number == 11)
    asked11 = true;

    if(current_number == 12)
    asked12 = true;

    return current_number;


} else overallNumber();

When I continuously call this function it just starts returning 'Undefined'. Any Solutions? Thx :)

User arrays to store your variables please, don't write in 20 lines of code what you can write in 3... — XCS, Feb 23 '17 at 13:09
I would suggest using an array to hold the used numbers, and keep generating a random number as long you find the number you generated is already in that used numbers array — Swimburger, Feb 23 '17 at 13:09
@ZakTheHat What have you tried? Show us what you tried and didn't work — XCS, Feb 23 '17 at 13:10
Check this to know how to do using arrays http://stackoverflow.com/questions/22510826/generating-random-number-in-array-without-repeatition-javascript or http://stackoverflow.com/questions/5836833/create-a-array-with-random-values-in-javascript — shubham agrawal, Feb 23 '17 at 13:12
@ZakTheHat Write it again, this code is written very poorly and it's very prone to bugs. The answer to "how to fix the bug in this code" is to re-write the code so that you don't have to add an `if` statement for each new question. — XCS, Feb 23 '17 at 13:13
I tried running you code and I don't see it returning undefined anytime. — Mirza, Feb 23 '17 at 13:38
Though the code is not what you should have coded (it should be like what sniels and Shubham gave)but if you see your code, the moment all 12 numbers are returned you will be stuck in an infinite loop. — Mirza, Feb 23 '17 at 13:50
@gRaWEty My question has been solved but anyway, It started returning 'undefined' even before it hit 12. — Zak The Hat, Feb 24 '17 at 10:06

score 1 · Accepted Answer · answered Feb 23 '17 at 13:17

1

The code should be self-explanatory, main thing is that you have to keep track of the used numbers using an array.

var number;
var maxNumber = 5;
var usedNumbers = [];

function getUnusedRandomNumber(){
    // keep generating a random number, until you find one that has not been used
    do{
      var randomNumber = getRandomNumber();
    }
    while(usedNumbers.indexOf(randomNumber) != -1);
    
    // store used numbers into array
    usedNumbers.push(randomNumber);
    return randomNumber;
}

function getRandomNumber() {
    var randomNumber = Math.round(Math.floor((Math.random() *     maxNumber) + 1)); 
    return randomNumber;
}

alert(getUnusedRandomNumber());
alert(getUnusedRandomNumber());
alert(getUnusedRandomNumber());
alert(getUnusedRandomNumber());
alert(getUnusedRandomNumber());

answered Feb 23 '17 at 13:17

Swimburger

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I've implemented your code but at the end my browser crashes. – Zak The Hat Feb 23 '17 at 13:20
No sorry that was my Code. – Zak The Hat Feb 23 '17 at 13:23
That's because you caused an endless loop. Notice how I called `getUnusedRandomNumber` only 5 times, and the maxNumber is also 5. The moment you will have used all numbers, the `while` loop will run infinitely causing your browser to freeze and crash. – Swimburger Feb 23 '17 at 13:23
@ZakTheHat, don't forget to accept an answer if it solves your question. – Swimburger Feb 23 '17 at 14:37

score 0 · Answer 2 · answered Feb 23 '17 at 13:34

A more condensed code is to generate random number without repetition is

var nums = [], numsLen = 12, maxNum = 12, num;
while (nums.length < numsLen) {
    num = Math.round(Math.random() * maxNum);
    if (nums.indexOf(num) === -1) {
        nums.push(num);
    }
}
console.log(nums);

Make sure a sum is asked only once (js)

2 Answers2