Function mergeOptions

static/vuejs/vue.esm.js:1193–1233

* Merge two option objects into a new one. * Core utility used in both instantiation and inheritance.

(
  parent,
  child,
  vm
)

 * Core utility used in both instantiation and inheritance.
 */
function mergeOptions (
  parent,
  child,
  vm
) {
  if (process.env.NODE_ENV !== 'production') {
    checkComponents(child);
  }
  normalizeProps(child);
  normalizeDirectives(child);
  var extendsFrom = child.extends;
  if (extendsFrom) {
    parent = typeof extendsFrom === 'function'
      ? mergeOptions(parent, extendsFrom.options, vm)
      : mergeOptions(parent, extendsFrom, vm);
  }
  if (child.mixins) {
    for (var i = 0, l = child.mixins.length; i < l; i++) {
      var mixin = child.mixins[i];
      if (mixin.prototype instanceof Vue$3) {
        mixin = mixin.options;
      }
      parent = mergeOptions(parent, mixin, vm);
    }
  }
  var options = {};
  var key;
  for (key in parent) {
    mergeField(key);
  }
  for (key in child) {
    if (!hasOwn(parent, key)) {
      mergeField(key);
    }
  }
  function mergeField (key) {
    var strat = strats[key] || defaultStrat;
    options[key] = strat(parent[key], child[key], vm, key);
  }
  return options
}

/**
 * Resolve an asset.