Showing a Thickbox (tb_show) does nothing

Question

I'm trying to add a media uploader to a widget/plugin and I'm at the stage where I need to add a picture from the media library (or upload a new one).

I added some javascript and added an event to a button in the plugin. This event gets fired (because the alert is displayed), but the thickbox does not show up.

Here's the JS code:

jQuery(document).ready(function() {
    jQuery('.upload_image_button').click(function() {
        alert('This alert is displayed');
        tb_show('Upload a Image', 'media-upload.php&type=image&TB_iframe=true', false);
        return false;
    });
});

Why isn't the Thickbox displayed?

WordPress version 4.1.1

Answer 1

Answer can be found here: https://stackoverflow.com/questions/13863087/wordpress-custom-widget-image-upload

Even though the problem described isn't exactly the same as I had, the code posted in the answer still helped me as that code actually does exactly what I needed.

I also think that I didn't originally find this answer as it's on the regular Stack Overflow and not the Wordpress part of it.