JQuery not working in Rails 5

I have a rails app. It has this button:

<button class="btn btn-primary" onClick="commentSlide()">Comments</button>

I want the button to change color on the click event, but Rails seems to be having trouble reading my JQuery. The first of the two functions below works. When I remove it, I get this error:

 Uncaught ReferenceError: commentSlide is not defined
at HTMLButtonElement.onclick ((index):81)

Here are my two functions. JavaScript works, JQuery does not. Help?

 function commentSlide(){
   alert("hello"); 
  }

 $(document).on('turbolinks:load', function(){

   function commentSlide(){
    $(this).css('backgroundColor', 'red'); 
   }
})

Here is the top section of my javascript file:

//= require jquery
//= require bootstrap-sprockets
//= require jquery_ujs
//= require turbolinks
//= require react
//= require react_ujs
//= require components
//= require_tree .