Front-end upload button

I’m reaching out for help after days of searching; I need users to be able to upload an image to be attached to a custom post. I find many hacks and descriptions about how to customize on admin page but none for the front-end. I was hoping to be able to tweak this code, but I think i get stuck on the wp.media bit that only runs in the admin pages.
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function open_media_window() {
if (this.window === undefined) {
this.window = wp.media({
title: ‘Insert a media’,
library: {type: ‘image’},
multiple: false,
button: {text: ‘Insert’}
});

var self = this; // Needed to retrieve our variable in the anonymous function below
this.window.on(‘select’, function() {
var first = self.window.state().get(‘selection’).first().toJSON();
wp.media.editor.insert(‘[myshortcode id=”‘ + first.id + ‘”]’);
});
}

this.window.open();
return false;
}

Source: http://www.sitepoint.com/adding-a-media-button-to-the-content-editor/