auto_complete_controller.js

import { Controller } from "stimulus"

export default class extends Controller {
  static targets = [ "source", "members" ]

  search(){
    var searchString = this.sourceTarget.value
    fetch(this.data.get("url")+"?query="+searchString)
    .then(response => response.text())
    .then(html => {
      this.membersTarget.innerHTML = html
    })
  }
}