Vue 3's Suspense component, ready for use in Vue 2.x (TypeScript)

Suspense.ts

import Vue from 'vue';

export const Suspense = Vue.extend({
  name: 'Suspense',
  data: () => ({
    resolved: false,
  }),
  async created() {
    const setupMethod = (this.$parent as any).setup;
    if (!setupMethod) {
      throw new Error(
        '[Suspense] No setup method found - make sure Suspense is at root ' +
          'level, just inside <template>'
      );
    }

    await setupMethod();
    this.resolved = true;
  },
  render(createElement) {
    return createElement(
      'div',
      this.resolved ? this.$slots.default : this.$slots.fallback
    );
  },
});

setup() needs to be a method:

method: {
  async setup() { }
}