cdao-pjet/app/javascript/controllers/subjects_controller.js

import ApplicationController from './application_controller'
export default class extends ApplicationController {
  connect () {
    super.connect()
  }

  renderSidenavAccordion () {
    var parent_id = this.element.dataset["subjectParentId"], $this = this, params = {}

    if (parent_id !== null && parent_id !== undefined && parent_id !== "") {
      params.parent_id = parent_id
    } else {
      params.is_root_only = true
    }

    $.get("/api/subjects.json", params, function (results, status) {
      if (status === "success") {
        $this.stimulate("SubjectsReflex#render_sidenav_accordion", results)
      }
    })
  }
}