Choices.js serves as a great example to understand how a third-party library might not work under Locker Service, and how to make it compatible with Locker Service. To understand this, let's take the choices.js vanilla code and integrate it into Lightning Components.
The choices.js library can be downloaded from https://github.com/jshjohnson/Choices/blob/master/assets/scripts/dist/choices.js.
The Lightning Component code is as follows:
<aura:component > <ltng:require styles="{!join(',',$Resource.ChoicesJS + '/choicesJS/base.min.css',$Resource.ChoicesJS + '/choicesJS/choices.min.css')}" scripts="{!$Resource.ChoicesJS + '/choicesJS/choices.min.js'}" afterScriptsLoaded="{!c.afterScriptsLoaded}"/> ...
