Rails 4: How to add external javascript file from other site in a specific page

Question

I am using turbolink (rails4) and following js link gets generated by application.js file in my pages header section

<script data-turbolinks-track="true" src="/assets/jquery.js?body=1"></script>
<script data-turbolinks-track="true" src="/assets/jquery_ujs.js?body=1"></script>
<script data-turbolinks-track="true" src="/assets/turbolinks.js?body=1"></script>
<script data-turbolinks-track="true" src="/assets/global.js?body=1"></script>

My application.js looks something like:

//= require jquery
//= require jquery_ujs
//= require turbolinks
//= require_tree .
//= require bootstrap.min.js
//= require respond.min.js

I want to add an external javascript file from OTHER site e.g. http://otherdomain.com/xyz.js in a specifc page of my site. Suppose I want to add this external js file ONLY in a specifc page http://mysite.com/profile And I want to add this js file ONLY in header part of the page. So how can I do that? Please don't suggest to save that external file locally as that is not an option for me.

Answer 1

A solution I'm looking at presently is injecting the script dynamically:

(function(d, script) {
    script = d.createElement('script');
    script.type = 'text/javascript';
    script.async = true;
    script.onload = function(){
        // remote script has loaded
    };
    script.src = 'http://www.google-analytics.com/ga.js';
    d.getElementsByTagName('head')[0].appendChild(script);
}(document));