Stimulus-based auto-expanding textarea

textarea_controller.js

import { Controller } from "stimulus"

export default class extends Controller {
  handle(event) {
    event.target.rows = event.target.value.split("\n").map((row) => {
      return Math.ceil((row.length + 1) / event.target.cols)
    }).reduce((acc, el) => acc + el) 
  }
}