Preloading images through iframes error

Question

Working on a script that is supposed to preload images by putting them into iframes. When a button is clicked, it will preload even more images and stop previous iframes from loading (no longer needed).

I am receiving two errors though that I cannot figure out:

1. Resource interpreted as Document but transferred with MIME type image/jpeg

2. Uncaught TypeError: Cannot read property 'contentWindow' of undefined

The latter error means my script is not fully working so my question is : what's wrong with my code? Here's a jsfiddle

 function preload(arrayOfImages) {
    $(arrayOfImages).each(function(){
        image_iframe[this] = $('<iframe />').appendTo('body')[0];
        image_iframe[this].onload = function() {
            console.log('Image Cached!');
            this.remove();
        };
        image_iframe[this].src = image_url[this];
    });
}

var image_iframe = [];
var image_url = []; 

image_url[1] = '/image.jpg';
image_url[2] = '/another-image.jpg';
image_url[...] = 'etc';

preload([2, 3]);
var current_url = 1;

function nextImage() {
    if( current_url <= 50) {
        current_url = current_url + 1;
        preload([current_url + 1, current_url + 2]);
        for (var z=1;z<current_url;z++) {
            image_iframe[z].contentWindow.stop();
            image_iframe[z].execCommand("Stop", false);
        }
    } else {
        window.location.replace("/");
    }
}

$('#remove').click(function(){ 
    nextImage();
});

The reason I'm using iframes is because I need a way to stop specific images from loading.
Cancel single image request in html5 browsers

EDIT: I think the problem is in how I define image_iframe[]
EDIT2: Gosh forgot that I started my preload at 2, which means that my loop (which starts at 1) gives an undefined error.

Answer 1

Resource interpreted as Document but transferred with MIME type image/jpeg

Fixed itself

Uncaught TypeError: Cannot read property 'contentWindow' of undefined

I started with array 2 in the preload but looped from 1