Function addClass

01.GettingStarted/js/vue.js:1329–1338

* Add class with compatibility for IE & SVG * * @param {Element} el * @param {String} cls

(el, cls)

   */

  function addClass(el, cls) {
    if (el.classList) {
      el.classList.add(cls);
    } else {
      var cur = ' ' + getClass(el) + ' ';
      if (cur.indexOf(' ' + cls + ' ') < 0) {
        setClass(el, (cur + cls).trim());
      }
    }
  }

  /**
   * Remove class with compatibility for IE & SVG