Move admin delete users confirmation dialog into JS file

Which fixes a CSP violation, but it was also always the preferred
solution. This wasn't done in the first place as we didn't have any JS
bundle set up for admin, that exists now, so it's time to move the
confirmation dialog triggering into the proper place.

h/static/scripts/admin-site.js

@@ -11,6 +11,12 @@ require('bootstrap');
 
 var page = require('page');
 
+var AdminUsersController = require('./admin-users');
+
+page('/admin/users', function() {
+  new AdminUsersController(document.body, window);
+});
+
 document.addEventListener('DOMContentLoaded', function () {
   page.start();
 });

h/static/scripts/admin-users.js

+'use strict';
+
+function AdminUsersController(element, window_) {
+  this._form = element.querySelector('#js-users-delete-form');
+
+  function confirmFormSubmit() {
+    return window_.confirm('This will permanently delete all the user\'s data. Are you sure?');
+  }
+
+  if (this._form) {
+    this._form.addEventListener('submit', function (event) {
+      if (!confirmFormSubmit()) {
+        event.preventDefault();
+      }
+    });
+  }
+}
+
+module.exports = AdminUsersController;

h/static/scripts/test/admin-users-test.js

+'use strict';
+
+var AdminUsersController = require('../admin-users');
+
+// helper to dispatch a native event to an element
+function sendEvent(element, eventType) {
+  // createEvent() used instead of Event constructor
+  // for PhantomJS compatibility
+  var event = document.createEvent('Event');
+  event.initEvent(eventType, true /* bubbles */, true /* cancelable */);
+  element.dispatchEvent(event);
+
+  return event;
+}
+
+describe('AdminUsersController', function () {
+  var root;
+  var form;
+
+  beforeEach(function () {
+    root = document.createElement('div');
+    root.innerHTML = '<form id="js-users-delete-form">' +
+                     '<input type="submit" id="submit-btn">';
+    form = root.querySelector('form');
+    document.body.appendChild(root);
+  });
+
+  afterEach(function () {
+    root.parentNode.removeChild(root);
+  });
+
+  it('it submits the form when confirm returns true', function () {
+    var fakeWindow = {confirm: sinon.stub().returns(true)};
+    new AdminUsersController(root, fakeWindow);
+
+    var event = sendEvent(form, 'submit');
+    assert.isFalse(event.defaultPrevented);
+  });
+
+  it('it cancels the form submission when confirm returns false', function () {
+    var fakeWindow = {confirm: sinon.stub().returns(false)};
+    new AdminUsersController(root, fakeWindow);
+
+    var event = sendEvent(form, 'submit');
+    assert.isTrue(event.defaultPrevented);
+  });
+});