Rails 5 JQuery Uncaught TypeError

Question

I have a JQuery error after deploying my app on Heroku

I use Rails 5.2. So this error prevents all the following js code to load.

Gemfile :

gem 'jquery-rails'
gem 'jquery-ui-rails'
gem 'bootstrap', '~> 4.0.0'

Application.js

//= require rails-ujs
//= require jquery
//= require jquery_ujs
//= require jquery-ui
//= require jquery.mCustomScrollbar.concat.min
//= require bootstrap
// require turbolinks
//= require_tree .
//

I precompiled my assets before deploying to heroku with :

RAILS_ENV=production bundle exec rake assets:precompile

The ERROR :

Uncaught TypeError: t.indexOf is not a function

I inspected the error, and it comes from this function :

/*!
 * Sizzle CSS Selector Engine v2.3.3
 * https://sizzlejs.com/
 *
 * Copyright jQuery Foundation and other contributors
 * Released under the MIT license
 * http://jquery.org/license
 *
 * Date: 2016-08-08
 */

Go to deployed page on heroku and open up the console to see the error.

Any ideas ?

Answer 1

This error might be caused by jQuery event aliases like .load , .unload or .error deprecated since jQuery 1.8 and removed in 3.0 .

Using lower versions like 2.1 will solve your problem.