Q:

How do I use jQuery and jQuery-ui with Parcel (bundler)?

I installed jquery(3.2.1) and jquery-ui-dist(1.12.1) via npm. (they're not included as script tags in html)
In client script I use:
window.$ = require('jquery');// plain jQuery stuff works fine
import 'jquery-ui-dist';     // breaks whole jQuery, with Error (missing module 8)

A:

I encountered similar issues today with an angularjs app & parcel-bundler.
It seems that parcel doesn't handle well (for now?) global variables introduced in external modules. Amongst other issues.
One way to go about it; you can use plain requires instead of imports like so:
var jquery = require("jquery");
window.$ = window.jQuery = jquery; // notice the definition of global variables here
require("jquery-ui-dist/jquery-ui.js");

$(function() {
  $("#datepicker").datepicker();
});

If you insist on using imports, you should create a separate file, call it for example import-jquery.js with the following content:
import jquery from "jquery";

export default (window.$ = window.jQuery = jquery);

and import it in your main file:
import "./import-jquery";
import "jquery-ui-dist/jquery-ui.js";

$(function() {
  $("#datepicker").datepicker();
});

I do hope we'll have better support of this in the near future.

