Function once

static/vuejs/vue.runtime.esm.js:238–246

* Ensure a function is called only once.

(fn)

 * Ensure a function is called only once.
 */
function once (fn) {
  var called = false;
  return function () {
    if (!called) {
      called = true;
      fn();
    }
  }
}

/*  */