Code review --- Random link with memory -- Javascript

Question

    var links = ["http://www.google.com/", "http://www.cnn.com/", "http://www.bbc.com/", "http://www.nbc.com/"];
    var random = Math.round(Math.random() * 4);
    var previous = [];
    previous.push(random);
    return previous

    for (var i = 0; i < previous.length; i++) {
        while (previous[i] == random) {
            random = Math.round(Math.random() * 4);
        }
}
    window.location = links[random];

I'm trying to make a code that will be used to lead users to a random site from a set of sites. This will be activated by a button in google sites, I just haven't gotten to the html part. Anyways, when I try to run this code in jsfiddle, the output is just a blank screen. Whats wrong? here's my logic

1. An array of the set sites.
2. 'random' picks a number between 0 and 4, which corresponds to the sites in the array
3. an empty array

4. This pushes 'random's output to the empty array

5. This for loop checks to see if there is any data in the empty array

6. While loop says "ok, if random chooses a number already in the array 'previous', I will run random again.
7. Once an unchosen number is outputted, a new window opens to the chosen site.

Sadly, it's not performing this way. Any tips?

Edit: Jsfiddle

Answer 1

I think a slight reworking of the code might do the trick with particular emphasis on removing the loop:

var links = ["http://www.google.com/", "http://www.cnn.com/", "http://www.bbc.com/", "http://www.nbc.com/"];
var previous = [];

function showLink() {
    if (previous.length !== links.length) {
      var random = Math.round(Math.random() * ((links.length - 1) - 0) + 0 );
      if (previous.indexOf(links[random]) > -1) {
        showLink(); 
      } else {
        console.log(links[random], previous)
        previous.push(links[random]);
      }
    } else {
        console.log('No more links');
    }
}

And at this point just keep calling showLink until you run out of links.

Demo

Answer 2

var links = ["http://www.google.com/", "http://www.cnn.com/", "http://www.bbc.com/", "http://www.nbc.com/"];
var random = Math.round(Math.random() * 4);
var previous = [];
previous.push(random);

for (var i = 0; i < previous.length; i++) {
    while (previous[i] == random) {
        random = Math.round(Math.random() * 4);
    }
}
window.location = links[random];

You were missing a bracket, and you had a return statement before your for loop. So of course it wasn't working since the code under the return statement was unreachable the way you had it written.