Plugin to wrap one-line JS script

I have an app along with a JS widget that users embed with a single line of JS code in the HEAD section on their own website.

Example::

<script>
!function(){window.onload=function(){var a=document.createElement("script");a.src='http://ift.tt/1MNUFaT',a.async=!0,a.onload=function(){__init('WIDGET_ID')},document.getElementsByTagName("head")[0].appendChild(a)}}();
</script>

I want to make it easy for wordpress users to install the widget on their site, even if they don't know how to manually include a script in their html file.

The script requires a WIDGET_ID and I imagine this could be entered from the Wordpress admin dashboard. All other configuration would be done from my site

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I'm a seasoned rails/node full stack developer, but for someone having absolutely no experience with PHP or Wordpress, how difficult/long would it be to create and distribute such as Wordpress plugin and where would be a good place to start?

via Chebli Mohamed