Function mergeDataOrFn

docs/themes/htx/source/js/vue.js:1148–1180

* Data

(parentVal, childVal, vm)

   * Data
   */
  function mergeDataOrFn(parentVal, childVal, vm) {
    if (!vm) {
      // in a Vue.extend merge, both should be functions
      if (!childVal) {
        return parentVal;
      }
      if (!parentVal) {
        return childVal;
      }
      // when parentVal & childVal are both present,
      // we need to return a function that returns the
      // merged result of both functions... no need to
      // check if parentVal is a function here because
      // it has to be a function to pass previous merges.
      return function mergedDataFn() {
        return mergeData(
          typeof childVal === "function" ? childVal.call(this, this) : childVal,
          typeof parentVal === "function" ? parentVal.call(this, this) : parentVal,
        );
      };
    } else {
      return function mergedInstanceDataFn() {
        // instance merge
        var instanceData = typeof childVal === "function" ? childVal.call(vm, vm) : childVal;
        var defaultData = typeof parentVal === "function" ? parentVal.call(vm, vm) : parentVal;
        if (instanceData) {
          return mergeData(instanceData, defaultData);
        } else {
          return defaultData;
        }
      };
    }
  }

  strats.data = function(parentVal, childVal, vm) {
    if (!vm) {