Function mergeVNodeHook

static/vuejs/vue.js:1708–1736

(def, hookKey, hook)

/*  */

function mergeVNodeHook (def, hookKey, hook) {
  var invoker;
  var oldHook = def[hookKey];

  function wrappedHook () {
    hook.apply(this, arguments);
    // important: remove merged hook to ensure it's called only once
    // and prevent memory leak
    remove(invoker.fns, wrappedHook);
  }

  if (!oldHook) {
    // no existing hook
    invoker = createFnInvoker([wrappedHook]);
  } else {
    /* istanbul ignore if */
    if (oldHook.fns && oldHook.merged) {
      // already a merged invoker
      invoker = oldHook;
      invoker.fns.push(wrappedHook);
    } else {
      // existing plain hook
      invoker = createFnInvoker([oldHook, wrappedHook]);
    }
  }

  invoker.merged = true;
  def[hookKey] = invoker;
}

/*  */