Function prepend

06.Router/basic/js/vue.js:1240–1246

* Prepend el to target * * @param {Element} el * @param {Element} target

(el, target)

   */

  function prepend(el, target) {
    if (target.firstChild) {
      before(el, target.firstChild);
    } else {
      target.appendChild(el);
    }
  }

  /**
   * Replace target with el