Get random element from array not more than once in a row

Question

Ive written this function which shows a random item from the array, and then tried to add a bit where it won't pick the same thing twice but now the text doesnt even show.

EDIT Thanks Pointy and Jonas W for spotting that. Working now

var lyrics = function(){
var olditem = document.getElementById("space").innerHTML
var item = space[Math.floor(Math.random() * space.length)];
while (olditem === item) {
    item = space[Math.floor(Math.random() * space.length)];
}
if (olditem !== item) {
    document.getElementById("space").innerHTML = item;      
}};

Check the browser's developer console for the syntax error in your code. — Pointy, Jan 19 '17 at 17:24
Wow I totally forgot that you can't have an else in a while loop — ThomasStringer, Jan 19 '17 at 17:28
Have a look at [this gist](https://gist.github.com/Daniel-Hug/74e4f1ea6d7067f0283b). Specifically the Loop Random function looks like what your looking for. — Web_Designer, Jan 19 '17 at 18:49

Jonas Wilms · Answer 1 · 2017-01-19T17:32:04.260

1

Why dont you do this

function lyrics(){
 var item = Math.floor(Math.random() * space.length);
 document.getElementById("space").innerHTML=space.splice(item,1)[0];
 }

That removes the item from the array, so it cant be used again...

edited Jan 19 '17 at 17:32

answered Jan 19 '17 at 17:27

Jonas Wilms

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have you tried to run it? – Igor Jan 19 '17 at 17:30
@Igor thanks for reminding me that splice returns an array... – Jonas Wilms Jan 19 '17 at 17:32
I don't think that OP wanted to modify `space` array, and the assignment is still wrong – Igor Jan 19 '17 at 17:33
@Igor : now i dont know what you mean... – Jonas Wilms Jan 19 '17 at 17:37
@igor 1 item != the first. Position is item wich is random... – Jonas Wilms Jan 19 '17 at 18:03

score 0 · Accepted Answer · answered Jan 19 '17 at 17:28

When it exits the while loop, there is an implied else already there. So I believe your else is causing it not to print. If you just remove that, it should be fine.

    var lyrics = function(){
        var olditem = document.getElementById("space").innerHTML
        var item = space[Math.floor(Math.random() * space.length)];
        while (olditem === item) {
            var item = space[Math.floor(Math.random() * space.length)];
        }
        document.getElementById("space").innerHTML = item;
    };

score 0 · Answer 3 · edited Jan 19 '17 at 18:45

0

var lyrics = function() {
    var olditem = document.getElementById("space").innerHTML;

    var item = space[Math.floor(Math.random() * space.length)];


    while (olditem === item) {
        item = space[Math.floor(Math.random() * space.length)];
    }

    document.getElementById("space").innerHTML = item;
};

edited Jan 19 '17 at 18:45

Web_Designer

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answered Jan 19 '17 at 17:31

Mitesh Pant

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Doesnt make sense to add another if + return at the end is senseless – Jonas Wilms Jan 19 '17 at 17:33
you are right about this, thanks – Mitesh Pant Jan 19 '17 at 17:34

score 0 · Answer 4 · edited May 23 '17 at 11:52

You can shuffle the array, then take items by order.
Shuffle function taken from here: How can I shuffle an array?

var data = [
  'one',
  'two', 
  'three',
  'four',
  'five'
]

function shuffle(a) {
    var j, x, i;
    for (i = a.length; i; i--) {
        j = Math.floor(Math.random() * i);
        x = a[i - 1];
        a[i - 1] = a[j];
        a[j] = x;
    }
}

var pos = 0;
shuffle(data);

var lyrics = function(){
    pos++;
    if (pos == data.length) {
      pos = 0;
      shuffle(data);
    }
    return data[pos];
}


console.log(lyrics());
console.log(lyrics());
console.log(lyrics());

Get random element from array not more than once in a row

4 Answers4