Unique Random Number Generator Javascript

Question

I'm trying to make a bingo game for fun. I've looked in a lot of places for a unique generator but I can't seem to find one. I've tried to make my own,but once it actually hits a number that's the same it does an infinite loop. I've tried a simple code that in theory should work but for some reason things pass through. What can I do!?

var bc = [];
for (var i = 0; i < 5; i++) {
  var r = Math.floor(Math.random()*20+1) + 0;
  if(!(r in bc)){
    bc.push(r);     
    }
    else
    {
    i--;
    }
}
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____________________________________________
____________________________________________
b1=0;
b2=0;
b3=0;
b4=0;
b5=0;
var bc = [b1,b2,b3,b4,b5]
var bnc = function(){
    var n = Math.floor(Math.random() * 5+1)+0;
    var n2 = Math.floor(Math.random() * 5+1)+0;
    b1 = n;
    var a1 = true;
    var as = false;
    while(a1){
        var c = n;
        if(c===b1||c===0 ||as!==false){
        c = n2;
        as=true;
        }
        if(c===b1||c===0&&as===true){
        c = n;
        as=false;
        }
            if(c!=b1){
            b2 = c;
            a1 = false;
            a2 = true;
        }
    }
};
bnc();
console.log("new1");
console.log(b1,b2,b3,b4,b5);
//_______________________________________
var bnc2 = function(){
    var n = Math.floor(Math.random() * 5+1)+0;
    var n2 = Math.floor(Math.random() * 5+1)+0;
    var a1 = true;
    var as = false;
    while(a1){
        var c = n;
        if(c===b1||c===b2||c===0&&as===false){
        c = n2;
        as=true;
        }
        if(c===b1||c===b2||c===0&&as===true){
        c = n;
        as=false;
        }
        if(c!=b1&&c!=b2){
            b3 = c;
            console.log("made it 1");
            a1 = false;
        }
    }
};
bnc2();
console.log("new2");
console.log(b1,b2,b3,b4,b5);

Solution 1

once it actually hits a number that's the same

It never should. Such algorithms take longer the longer they run. You should take a different approach:

Put all possible numbers into a pool. Once you draw a number, remove it from the pool. Just like it's done in real life.

var pool = [1, 2, 3, 4, 5];
var getNumber = function () {
    if (pool.length == 0) {
        throw "No numbers left";
    }
    var index = Math.floor(pool.length * Math.random());
    var drawn = pool.splice(index, 1);
    return drawn[0];
};

Solution 2

I would rather do it with something like this:

http://jsfiddle.net/YC58s/

generate = function(length)
{
    var arr = [];
    var n;
    for(var i=0; i<length; i++)
    {
        do
            n = Math.floor(Math.random()*20+1);
        while(arr.indexOf(n) !== -1)

       arr[i] = n;
    }

    return arr;
}

Comments

[apelsinapa]

It wouldn't be entirely wrong with some comments and/or description of what the functions is supposed to do since its so much code. You want to generate a sequence of unique random? It seems to be alot of code just for that...

[Kane]

You could easily adapt one of these answers if you need a unique random number: stackoverflow.com/questions/105034/…

[nnnnnn]

Hint about your first for loop: the in operator doesn't do what you think it does (it tests property names, not property values).

[DShah]

Below link shows how to generate unique number with defined quantity of numbers. It is really simple logic at Javascript layer. blog.chrometaphore.com/2012/01/17/…

[Trent Braswell]

Could you explain how this works. I get the loop, the return, the vars, but the while statement. How does that work, why does it not make repeats?

[apelsinapa]

@TrentBraswell the while loop is a do/while. Which means it will run the inline statement and setting the n to a random number, before checking the criterium. The criterium evaluates if there is such a value in the array. indexOf(n) returns the integer key for the value of n if it exists in the array, otherwise it returns -1. Thus, running the loop again if indexOf does not return -1.