function _createElement()

in views/vue.js [4432:4520]
79 lines of code
25 McCabe index (conditional complexity)

  function _createElement(context, tag, data, children, normalizationType) {
    if (isDef(data) && isDef(data.__ob__)) {
      "development" !== "production" &&
        warn(
          "Avoid using observed data object as vnode data: " +
            JSON.stringify(data) +
            "\n" +
            "Always create fresh vnode data objects in each render!",
          context
        );
      return createEmptyVNode();
    }
    // object syntax in v-bind
    if (isDef(data) && isDef(data.is)) {
      tag = data.is;
    }
    if (!tag) {
      // in case of component :is set to falsy value
      return createEmptyVNode();
    }
    // warn against non-primitive key
    if (
      "development" !== "production" &&
      isDef(data) &&
      isDef(data.key) &&
      !isPrimitive(data.key)
    ) {
      {
        warn(
          "Avoid using non-primitive value as key, " +
            "use string/number value instead.",
          context
        );
      }
    }
    // support single function children as default scoped slot
    if (Array.isArray(children) && typeof children[0] === "function") {
      data = data || {};
      data.scopedSlots = { default: children[0] };
      children.length = 0;
    }
    if (normalizationType === ALWAYS_NORMALIZE) {
      children = normalizeChildren(children);
    } else if (normalizationType === SIMPLE_NORMALIZE) {
      children = simpleNormalizeChildren(children);
    }
    let vnode, ns;
    if (typeof tag === "string") {
      let Ctor;
      ns = (context.$vnode && context.$vnode.ns) || config.getTagNamespace(tag);
      if (config.isReservedTag(tag)) {
        // platform built-in elements
        vnode = new VNode(
          config.parsePlatformTagName(tag),
          data,
          children,
          undefined,
          undefined,
          context
        );
      } else if (
        isDef((Ctor = resolveAsset(context.$options, "components", tag)))
      ) {
        // component
        vnode = createComponent(Ctor, data, context, children, tag);
      } else {
        // unknown or unlisted namespaced elements
        // check at runtime because it may get assigned a namespace when its
        // parent normalizes children
        vnode = new VNode(tag, data, children, undefined, undefined, context);
      }
    } else {
      // direct component options / constructor
      vnode = createComponent(tag, data, context, children);
    }
    if (Array.isArray(vnode)) {
      return vnode;
    } else if (isDef(vnode)) {
      if (isDef(ns)) {
        applyNS(vnode, ns);
      }
      if (isDef(data)) {
        registerDeepBindings(data);
      }
      return vnode;
    } else {
      return createEmptyVNode();
    }
  }