CODEWITHSUNDEEP
javascript
Dylan McGrath
Dylan McGrath

Reputation: 151

Javascript Non-Repeating Number Generator Sometimes Returns Multiple Numbers

I'm trying to create a random Non-Repeating Number Generator for numbers up to 13. When I run the following function I get varying out puts, here are the results of running the function 5 times using a button click, and the code. I can't understand why it's repeating some numbers.

var checkIfRandom = new Array();



    function getRandom(){
        var randomNum= Math.floor(Math.random()*13);
        if(checkIfRandom.indexOf(randomNum) !== -1){
            getRandom();
    }else if(checkIfRandom.indexOf(randomNum)==-1){
        checkIfRandom.push(randomNum);
    }

        console.log(randomNum);

    };

//results
2 //Click 1
7, 2 //Click 2
6 //Click 3
1 //Click 4 
5,7,1 //Click 5
[2, 7, 6, 1, 5]//After 5 clicks I logged the checkIfRandom array to the console in chrome.

Upvotes: 1

Views: 54

Answers (2)

IMTheNachoMan
IMTheNachoMan

Reputation: 5821

// empty array with size we want
var randomList = new Array(13).join("|").split("|");

function getRandom()
{
    // if "" doesn't exist then every number has been used
    if(randomList.indexOf("") === -1) return -1;

    // get random number
    var randomNum = Math.floor(Math.random() * randomList.length);

    // if its already used then get a new one
    if(randomList[randomNum]) return getRandom();

    // save the random num and return it
    randomList[randomNum] = true;
    return randomNum;
}

http://jsfiddle.net/vpkspna4/

Upvotes: 0

SexmanTaco
SexmanTaco

Reputation: 309

You're using recursion, which means it's storing the previous, non-unique numbers in the stack and is still logging them. Move the console.log() into the else if so it reads:

function getRandom(){
    var randomNum= Math.floor(Math.random()*13);
    if(checkIfRandom.indexOf(randomNum) !== -1){
        getRandom();
}else if(checkIfRandom.indexOf(randomNum)==-1){
    checkIfRandom.push(randomNum);
    console.log(randomNum);
}
};

Upvotes: 1

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