如何检查集合中使用了哪个变量？

Question

I'm trying to work a script to check if a called variable is currently being used. Here is an example of the code.

function tellAJoke()
{
var collective = ["variable 1", 
            "Variable 2",   
            "Variable 3",   
            "Variable 4"]
var destination = document.getElementById('destination')
destination.innerHTML = collective[Math.floor(Math.random() * collective.length)];
}

How would I check which variable is being used? This is to prevent the same variable from being called again.

Answer 1

Instead of trying to find a new value each time, just shuffle your array randomly on page load and then iterate over it. This way you will have a different order each time the page gets loaded but you'll never show the same thing twice in a row. If you are done with the array, simply start from the beginning

small example: http://jsfiddle.net/Elak/8JsD4/

var collective = ["variable 1",
        "Variable 2",
        "Variable 3",
        "Variable 4"]

var shuffle = function (arr) {
    for (var j, x, i = arr.length; i; j = parseInt(Math.random() * i), x = arr[--i], arr[i] = arr[j], arr[j] = x);
    return arr;
}

var newCol = shuffle(collective);
var index = 0;
setInterval(function () {
    if (index >= newCol.length) index = 0;
    $("#out").text(newCol[index]);
    index++;
}, 1000);